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In the UK. They are roughly 1.5mm long, appear to crawl much more than fly, and seem to live in the soil of indoor potted plants. They are fast and tiny, so apologies for very shallow DOF. The first is on an aloe, the second is on a pot. They really like the soil around some capsicum plants.
Those look to me like fungus gnats. If you're looking to get rid of them, I've heard that putting a layer of rice hulls on top of the soil keeps them from reproducing. From what little I've read my identification doesn't go much deeper than superfamily, taxonomically, but it's a least a common name to work from.
Soil Dwelling Pests
Beneficial nematodes seek out and kill all stages of harmful soil-dwelling insects. They can be used to control a broad range of soil-inhabiting insects and above-ground insects in their soil-inhabiting stage of life. More than 200 species of insect pests from 100 insect families are susceptible to these insect predators.
They are a natural and effective alternative to chemical pesticides, and have no detrimental affect on non-target species such as ladybugs, earth worms and other helpful garden insects.Finally, there is no evidence that parasitic nematodes or their symbiotic bacteria can develop in vertebrates. This makes nematode use for insect pest control safe and environmentally friendly. The United States Environmental Protection Agency (EPA) has ruled that nematodes are exempt from registration because they occur naturally and require no genetic modification by man.
Beneficial nematodes can be applied anytime during the year when soil-dwelling insects are present and soil tempertures are above 52-F during the day. Beneficial nematodes seek out and kill over 200 pest insects in the soil. They are a natural effective alternative to chemical pesticides.
100 mil. Steinernema carpocapsae & Heterorhabditis bacteriophora nematodes
150 Million Nematodes mixed SC, HB, and SF.
Heterorhabditis Bacteriophora Nematodes (HB)
Are most effective against Japanese Beetles, Grubs, Weevils, and many other target pests in lawn and garden. They burrow down in the soil to a depth of 7", have shown superior host-seeking abilities in looking for deep soil- dwelling pests.
Target pests include: Cucumber Beetle, Grubs, Gall midge, Strawberry Rootweevil, May/June Beetle, Masked Chafer, Cranberry Rootworm, Flea, Scarab and Japanese beetles, Straw- berry Root and Black-vine Weevils, Chafer, Squash Bugs, Leaf Beetles, Termite, Cutworms, White Grubs, Algae Gnats, Black Fly, Potato Tubeworm, Meal Worm, Bark Beetle, Corn Root Weevil, Fire Ant, sting Bugs, Pine Beetle, Gall Gnats, Gypsy Moth, Corn Root Worm, Billbug, Colorado Potato Beetle, Thrips, Ants and termites (apply directly to mound and nest areas),and many other deep soil dwelling insects.
They are highly efficent when the pest is more widely dispersed in the soil because they have a "tooth" to rupture the insect's skin and enter through the insect's body wall and openings.
Steinernema Carpocapse Nematodes (SC)
Kills pre-adult fleas in the yard, and pet run areas and soil. It's most effective against flea larvae and caterpillars in lawns, garden soil, and under trees where larvae pupate. They stay near the surface waiting to ambush surface dwelling pests. Steinernema is the most widely researched species for insect control. It is the most readily available for yard and Garden use because it is easier to rear and handle. In field applications, Steinernema carpocapsae tend to be most effective against caterpillar larvae. In laboratory and field trials, it has controlled sod webworms, cutworms and certain borers (raspberry crown borer, carpenter worm). It also has been effective against billbug larvae in Colorado State University trials. Other research indicates that adult billbugs may be controlled as well. Steinernema are less effective against white grubs, root maggots, rootworms and black vine weevil. Unfortunately, some commercial products make claims of effective control of some pest species based on research conducted solely in artificial environments these often do not reflect performance in the field.
Target pests include: Fleas, Dog and cat flea larvae, Codling Moth, Cutworm, Armyworm, Leafminer, Bluegrass billbugs, termites, ants, Sod Webworm, Mole Cricket, some caterpillar pests, Billbug, Flies, ArmyWorms, Loopers, European Crane Fly, Cranberry Girdler and many other surface dwellers.
Steinernema Feltiae Nematodes (SF)
Are the most effective against larval control of several fly species (sciaridae, phoridae, leaf miners, domestic fly and also of some moth larvae. They patrol the top 3" of the soil.
Target pests include: Fungus Gnat, Mushroom Flies, Fruit Flies, Flea Beetles, Saw Flies, Tachina Flies, Crane Flies, Shore Flies and fruit flies.
They are effective against some plant parasitic nematodes, particularly root-knot nematodes.
Researchers Turn Mosquitoes Into Flying Vaccinators
Here's a study to file under "unworkable but very cool." A group of Japanese researchers has developed a mosquito that spreads vaccine instead of disease. Even the researchers admit, however, that regulatory and ethical problems will prevent the critters from ever taking wing—at least for the delivery of human vaccines.
Scientists have dreamed up various ways to tinker with insects' DNA to fight disease. One option is to create strains of mosquitoes that are resistant to infections with parasites or viruses, or that are unable to pass the pathogens on to humans. These would somehow have to replace the natural, disease-bearing mosquitoes, which is a tall order. Another strategy closer to becoming reality is to release transgenic mosquitoes that, when they mate with wild-type counterparts, don't produce viable offspring. That would shrink the population over time.
The new study relies on a very different mechanism: Use mosquitoes to become what the scientists call "flying vaccinators." Normally, when mosquitoes bite, they inject a tiny drop of saliva that prevents the host's blood from clotting. The Japanese group decided to add an antigen-a compound that triggers an immune response-to the mix of proteins in the insect's saliva.
A group by led by molecular geneticist Shigeto Yoshida of Jichi Medical University in Tochigi, Japan, identified a region in the genome of Anopheles stephensi-a malaria mosquito-called a promoter that turns on genes only in the insects' saliva. To this promoter they attached SP15, a candidate vaccine against leishmaniasis, a parasitic disease spread by sand flies that can cause skin sores and organ damage. Sure enough, the mosquitoes produced SP15 in their saliva, the team reports in the current issue of Insect Molecular Biology. And when the insects were allowed to feast on mice, the mice developed antibodies against SP15.
Antibody levels weren't very high, and the team has yet to test whether they protect the rodents against the disease. (Only very few labs have the facilities for so-called challenge studies with that disease, says Yoshida.) In the experiment, mice were bitten some 1500 times on average that may seem very high, but studies show that in places where malaria is rampant, people get bitten more than 100 times a night, Yoshida points out. In the meantime, the group has also made mosquitoes produce a candidate malaria vaccine.
Other researchers are wowed by the achievement. "The science is really beautiful," says Jesus Valenzuela of the National Institute of Allergy and Infectious Diseases in Bethesda, Maryland, who developed the SP15 vaccine. David O'Brochta, an insect molecular geneticist at the University of Maryland, College Park, calls it "a fascinating proof of concept."
So why won't it fly? There's a huge variation in the number of mosquito bites one person received compared with the next, so people exposed to the transgenic mosquitoes would get vastly different doses of the vaccine it would be a bit like giving some people one measles jab and others 500 of them. No regulatory agency would sign off on that, says molecular biologist Robert Sinden of Imperial College London. Releasing the mosquitoes would also mean vaccinating people without their informed consent, an ethical no-no. Yoshida concedes that the mosquito would be "unacceptable" as a human vaccine-delivery mechanism.
However, flying vaccinators-or "flying syringes" as some have dubbed them -may have potential in fighting animal disease, says O'Brochta. Animals don't need to give their consent, and the variable dosage would be less of a concern.
Secondary Production: Activities of Heterotrophic Organisms—The Soil Fauna
David C. Coleman , . Paul F. Hendrix , in Fundamentals of Soil Ecology (Second Edition) , 2004
Many of the true flies can be considered soil insects , at least in some stage of their life histories. At least 75 of the 108 dipteran families in North America have some contact with soil ecosystems ( McAlpine, 1990 ). This listing excludes strictly aquatic families, aboveground herbivores, and some parasitic species. Many species that live in aboveground habitats pupate in the soil, thus participating, involuntarily, in soil food webs. McAlpine (1990) provides a well-illustrated key to families of Diptera that have relations with soil systems.
Many species of fly larvae are important saprovores in soils. They are restricted to moist situations rich in organic matter. Some larvae are predatory and these have adaptations to reduce moisture loss they occur in drier situations ( Teskey, 1990 ). Fly larvae have a major impact on decomposition rates of carrion. Together with some beetle species, maggots of various types hasten the decomposition rate significantly. When Payne (1965) used window screen to exclude insects from decaying corpses of baby pigs, the bodies became mummified and decomposed slowly compared with corpses exposed to insect attack. Fly larvae are also important in forensic entomology, where their identification has been helpful in determining time of death of human corpses ( Catts and Haskell, 1990 ).
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What kind of soil-dwelling flying insect is this? - Biology
Many bugs, known as arthropods, make their home in the soil. They get their name from their jointed (arthros) legs (podos). Arthropods are invertebrates, that is, they have no backbone, and rely instead on an external covering called an exoskeleton.
Arthropods range in size from microscopic to several inches in length. They include insects, such as springtails, beetles, and ants crustaceans such as sowbugs arachnids such as spiders and mites myriapods, such as centipedes and millipedes and scorpions.
Nearly every soil is home to many different arthropod species. Certain row-crop soils contain several dozen species of arthropods in a square mile. Several thousand different species may live in a square mile of forest soil.
Arthropods can be grouped as shredders, predators, herbivores, and fungal-feeders, based on their functions in soil. Most soil-dwelling arthropods eat fungi, worms, or other arthropods. Root-feeders and dead-plant shredders are less abundant. As they feed, arthropods aerate and mix the soil, regulate the population size of other soil organisms, and shred organic material.
Many large arthropods frequently seen on the soil surface are shredders. Shredders chew up dead plant matter as they eat bacteria and fungi on the surface of the plant matter. The most abundant shredders are millipedes and sowbugs, as well as termites, certain mites, and roaches. In agricultural soils, shredders can become pests by feeding on live roots if sufficient dead plant material is not present.
Predators and micropredators can be either generalists, feeding on many different prey types, or specialists, hunting only a single prey type. Predators include centipedes, spiders, ground-beetles, scorpions, skunk-spiders, pseudoscorpions, ants, and some mites. Many predators eat crop pests, and some, such as beetles and parasitic wasps, have been developed for use as commercial biocontrols.
Numerous root-feeding insects, such as cicadas, mole-crickets, and anthomyiid flies (root-maggots), live part of all of their life in the soil. Some herbivores, including rootworms and symphylans, can be crop pests where they occur in large numbers, feeding on roots or other plant parts.
|Figure 14: The symphylan, a relative of the centipede, feeds on plant roots and can become a major crop pest if its population is not controlled by other organisms. |
Credit: Ken Gray Collection, Department of Entomology, Oregon State University, Corvallis.
Arthropods that graze on fungi (and to some extent bacteria) include most springtails, some mites, and silverfish. They scrape and consume bacteria and fungi off root surfaces. A large fraction of the nutrients available to plants is a result of microbial-grazing and nutrient release by fauna.
WHAT IS IN YOUR SOIL?
If you would like to see what kind of organisms are in your soil, you can easily make a pitfall trap to catch large arthropods, and a Burlese funnel to catch small arthropods.
Make a pitfall trap by sinking a pint- or quart-sized container (such as a yogurt cup) into the ground so the rim is level with the soil surface. If desired, fashion a roof over the cup to keep the rain out, and add 1/2 of an inch of non-hazardous antifreeze to the cup to preserve the creatures and prevent them from eating one another. Leave in place for a week and wait for soil organisms to fall into the trap.
To make a Burlese funnel, set a piece of 1/4 inch rigid wire screen in the bottom of a funnel to support the soil. (A funnel can be made by cutting the bottom off a plastic soda bottle.) Half fill the funnel with soil, and suspend it over a cup with a bit of anti-freeze or ethyl alcohol in the bottom as a preservative.
Suspend a light bulb about 4 inches over the soil to drive the organisms out of the soil and into the cup. Leave the light bulb on for about 3 days to dry out the soil. Then pour the alcohol into a shallow dish and use a magnifying glass to examine the organisms.
WHAT DO ARTHROPODS DO?
Although the plant feeders can become pests, most arthropods perform beneficial functions in the soil-plant system.
Shred organic material. Arthropods increase the surface area accessible to microbial attack by shredding dead plant residue and burrowing into coarse woody debris. Without shredders, a bacterium in leaf litter would be like a person in a pantry without a can-opener eating would be a very slow process. The shredders act like can-openers and greatly increase the rate of decomposition. Arthropods ingest decaying plant material to eat the bacteria and fungi on the surface of the organic material.
Stimulate microbial activity. As arthropods graze on bacteria and fungi, they stimulate the growth of mycorrhizae and other fungi, and the decomposition of organic matter. If grazer populations get too dense the opposite effect can occur populations of bacteria and fungi will decline. Predatory arthropods are important to keep grazer populations under control and to prevent them from over-grazing microbes.
Mix microbes with their food. From a bacteriums point-of-view, just a fraction of a millimeter is infinitely far away. Bacteria have limited mobility in soil and a competitor is likely to be closer to a nutrient treasure. Arthropods help out by distributing nutrients through the soil, and by carrying bacteria on their exoskeleton and through their digestive system. By more thoroughly mixing microbes with their food, arthropods enhance organic matter decomposition.
Mineralize plant nutrients. As they graze, arthropods mineralize some of the nutrients in bacteria and fungi, and excrete nutrients in plant-available forms.
Enhance soil aggregation. In most forested and grassland soils, every particle in the upper several inches of soil has been through the gut of numerous soil fauna. Each time soil passes through another arthropod or earthworm, it is thoroughly mixed with organic matter and mucus and deposited as fecal pellets. Fecal pellets are a highly concentrated nutrient resource, and are a mixture of the organic and inorganic substances required for growth of bacteria and fungi. In many soils, aggregates between 1/10,000 and 1/10 of an inch (0.0025mm and 2.5mm) are actually fecal pellets.
Burrow. Relatively few arthropod species burrow through the soil. Yet, within any soil community, burrowing arthropods and earthworms exert an enormous influence on the composition of the total fauna by shaping habitat. Burrowing changes the physical properties of soil, including porosity, water-infiltration rate, and bulk density.
Stimulate the succession of species. A dizzying array of natural bio-organic chemicals permeates the soil. Complete digestion of these chemicals requires a series of many types of bacteria, fungi, and other organisms with different enzymes. At any time, only a small subset of species is metabolically active only those capable of using the resources currently available. Soil arthropods consume the dominant organisms and permit other species to move in and take their place, thus facilitating the progressive breakdown of soil organic matter.
Control pests. Some arthropods can be damaging to crop yields, but many others that are present in all soils eat or compete with various root- and foliage-feeders. Some (the specialists) feed on only a single type of prey species. Other arthropods (the generalists), such as many species of centipedes, spiders, ground-beetles, rove-beetles, and gamasid mites, feed on a broad range of prey. Where a healthy population of generalist predators is present, they will be available to deal with a variety of pest outbreaks. A population of predators can only be maintained between pest outbreaks if there is a constant source of non-pest prey to eat. That is, there must be a healthy and diverse food web.
A fundamental dilemma in pest control is that tillage and insecticide application have enormous effects on non- target species in the food web. Intense land use (especially monoculture, tillage, and pesticides) depletes soil diversity. As total soil diversity declines, predator populations drop sharply and the possibility for subsequent pest outbreaks increases.
WHERE DO ARTHROPODS LIVE?
The abundance and diversity of soil fauna diminishes significantly with soil depth. The great majority of all soil species are confined to the top three inches. Most of these creatures have limited mobility, and are probably capable of cryptobiosis, a state of suspended animation that helps them survive extremes of temperature, wetness, or dryness that would otherwise be lethal.
As a general rule, larger species are active on the soil surface, seeking temporary refuge under vegetation, plant residue, wood, or rocks. Many of these arthropods commute daily to forage within herbaceous vegetation above, or even high in the canopy of trees. (For instance, one of these tree-climbers is the caterpillar-searcher used by foresters to control gypsy moth). Some large species capable of true burrowing live within the deeper layers of the soil.
Below about two inches in the soil, fauna are generally small 1/250 to 1/10 of an inch. (Twenty-five of the smallest of these would fit in a period on this page.) These species are usually blind and lack prominent coloration. They are capable of squeezing through minute pore spaces and along root channels. Sub-surface soil dwellers are associated primarily with the rhizosphere (the soil volume immediately adjacent to roots).
ABUNDANCE OF ARTHROPODS
A single square yard of soil will contain 500 to 200,000 individual arthropods, depending upon the soil type, plant community, and management system. Despite these large numbers, the biomass of arthropods in soil is far less than that of protozoa and nematodes.
In most environments, the most abundant soil dwellers are springtails and mites, though ants and termites predominate in certain situations, especially in desert and tropical soils. The largest number of arthropods are in natural plant communities with few earthworms (such as conifer forests). Natural communities with numerous earthworms (such as grassland soils) have the fewest arthropods. Apparently, earthworms out-compete arthropods, perhaps by excessively reworking their habitat or eating them incidentally. However, within pastures and farm lands arthropod numbers and diversity are generally thought to increase as earthworm populations rise. Burrowing earthworms probably create habitat space for arthropods in agricultural soils.
BUG BIOGRAPHY: Springtails
Springtails are the most abundant arthropods in many agricultural and rangeland soils. populations of tens of thousands per square yard are frequent. When foraging, springtails walk with 3 pairs of legs like most insects, and hold their tail tightly tucked under the belly. If attacked by a predator, body fluid rushes into the tail base, forcing the tail to slam down and catapult the springtail as much as a yard away. Springtails have been shown to be beneficial to crop plants by releasing nutrients and by feeding upon diseases caused by fungi.
The challenges in adopting the traditional methods described in the previous section to insect flight are manifold and only briefly described here. Determined primarily by their variation in size, flying insects operate over a broad range of Reynolds numbers from approximately 10 to 10 5 (Dudley, 2000). For comparison, the Reynolds number of a swimming sperm is approximately 10 –2 , a swimming human being is 10 6 and a commercial jumbo jet at 0.8 Mach is 10 7 . At the high Reynolds numbers characteristic of the largest insects, the importance of the viscous term in equation 2 may be negligible and, as with aircraft, flows and forces may be governed by its inviscid form (the Euler equation). Such simplifications may not always be possible for most species, whose small size translates into low Reynolds numbers. This is not to say that viscous forces dominate in small insects. To the contrary, even at a Reynolds number of 10,inertial forces are roughly an order of magnitude greater than viscous forces. However, viscous effects become more important in structuring flow and thus cannot be ignored. Due to these viscous effects, the principles underlying aerodynamic force production may differ in small vs large insects. For tiny insects, small perturbations in the fluid may be more rapidly dissipated due to viscous resistance to fluid motion. However, for larger insects operating at higher Reynolds numbers, small perturbations in the flow field accumulate with time and may ultimately result in stronger unsteadiness of the surrounding flows. Even with the accurate knowledge of the smallest perturbations, such situations are impossible to predict analytically because there may be several possible solutions to the flow equations. In such cases,strict static and dynamic initial and boundary conditions must be identified to reduce the number of solutions to a few meaningful possibilities.
What kind of soil-dwelling flying insect is this? - Biology
Tim Shepherd/Oxford Scientific Films
There are about 119,500 known species of flies and they make up the fourth largest insect order, after the beetles, butterflies and moths, and bees and wasps. The order is divided into three main suborders. The most primitive suborder is distinguished in that the pupae are obtect, covered by an outer shell with appendages more-or-less glued to the body. In this group, the adult flies are generally slender insects with long antennae and finely veined wings, such as mosquitoes, crane flies, midges, March flies, and black flies. The second suborder is distinguished by somewhat more advanced species that have coarctate pupae, that is, housed within a hard capsule formed by the second to last larval skin. The adult emerges from a T-shaped opening in the pupal case. This group contains the robber, horse, and bee fly families and several others. The final suborder contains highly advanced members with fewer veins in the wings and wide diversity of lifestyles. The adults generally have stouter bodies and short antennae among them are the house fly, bot flies, fruit flies, and the tsetse fly.
Some primitive species of flies do not feed as adults and their mouthparts are very small. However, most flies have highly developed mouthparts that are used for specialized feeding on a wide array of materials. Mosquitoes have piercing-sucking mouthparts, modified into structures similar to a hypodermic needle in a flexible sheath, and feed on blood and nectar. Horse flies have scissorlike cutting blades, which both tear and pierce a victim's flesh. The bee fly has a long proboscis that extends deep into flowers to draw up nectar. Many advanced flies have a soft proboscis, a trunklike organ that branches into a two-lobed tip. The proboscis is applied to wet surfaces, as is commonly seen in the house fly, and sucks up fluids by means of a capillary action and a bellowslike pump in the head.
The six legs of flies each have a tarsus, or foot, with a pair of tonglike claws used for gripping rough surfaces. Beneath the claws is a fleshy, glandular adhesive pad called a pulvillus, which is used on smooth surfaces and accounts for the house fly's feat of walking across ceilings.
Flies are the only major group of insects that have only a single pair of wings. The rear wings are vestigial, reduced to small knoblike structures known as halteres. The halteres vibrate vertically at the same rate as the forewings and act as gyroscopes. They enable the powerful forewings to thrust the insect forward without sending it into a nose dive, and may act as rudders, to keep the insect on a steady course.
Powderpost beetles are second only to termites in their ability to damage dry, seasoned wood. And yet, customers often receive conflicting opinions about whether the insects and/or damage they are seeing is indeed due to powderpost beetles. Mistakes also are made in determining whether the infestation is active, and if so, how it should be managed. As a result, the pests may cause considerable confusion for homeowners, wood suppliers, manufacturers, builders, and even pest control companies. This publication explains how to make those determinations.
Types and Habits
“Powderpost beetle” is a term used to describe several species of small (1/8-3/4 inch long) insects that reduce wood to a flour-like powder (Figure 1). The developing grub-like larvae inflict damage as they create narrow, meandering tunnels in wood as they feed. Tunneling and larval development take place entirely below the wood surface. Infestations typically are discovered after noticing powder, accompanied by small, round “shot holes” in the wood surface. These are exit holes where adult beetles have chewed out of the wood after completing their development. Newly emerged adults mate and lay eggs on or below the surface of bare, unfinished wood. The eggs hatch into tiny larvae that bore into the wood, emerging as adults one to five years later, usually during late winter, spring or summer depending upon species. Customers are more likely to see damage, rather than the beetles themselves, because the adults are cryptic and active mainly at night. Occasionally, the beetles may be found near damaged wood, or on windowsills since some are attracted to light.
Fig. 1: Powderpost beetles produce small round holes accompanied by wood powder.
The three most destructive groups of powderpost beetles are the lyctids , anobiids , and bostrichids . Each group contains several species capable of damaging wood materials.
Lyctid powderpost beetles are small (1/16-1/4 inch), narrow and elongated, reddish-brown to black beetles (Figure 2). Their emergence holes are round and about the size of a pinhead. The powdery dust feels like flour or fine talc, and often accumulates in small piles beneath or beside emergence holes. Lyctid powderpost beetles attack only wood products manufactured from hardwood (broadleaf) trees such as oak, ash, walnut, hickory, poplar or cherry. Consequently, infestations are often associated with flooring, paneling, molding, window and doorframes, and furniture. Lyctids do not normally infest structural building components (studs, joists, beams, etc.) since these usually consist of non-vulnerable softwoods (conifers/evergreens). Tropical hardwoods are especially prone to lyctid infestation because of poor storage and drying practices before importation. Articles made from bamboo are commonly infested as well. Plywood fabricated from hardwood veneers may be attacked, but damage is usually confined to the hardwood layer in which eggs were initially laid since the larvae tend to avoid glues and resins. Construction plywood (used for subfloors, sheathing, etc.), is made from softwood and is unsuitable for infestation by lyctids.
Fig. 2 Lyctid powderpost beetles. The powder is the consistency of flour.
After emergence and mating, female beetles locate susceptible wood to lay eggs. Ten to 50 eggs per female are inserted into the tiny pores and vessels of unfinished wood. Surfaces that are stained, varnished, waxed or painted are immune from attack (although larvae already within infested wood may emerge through finished surfaces). Also avoided are softwoods such as pine. Before depositing eggs, female lyctid beetles “test” the suitability of wood for the larvae, which require starches and sugars for development. If the starch content of wood is insufficient (less than about 3 percent), the females will not use it for egg laying.
Lower starch levels also make it harder for the larvae to complete their development. In newly seasoned wood with abundant nutrients, egg to adult development occurs in less than a year. Conversely, as wood ages, starch content declines and development slows to the point where some beetles may not emerge for two or more years if at all. Consequently, infestations eventually cease and die off even without intervention — an important factor when weighing treatment options (see ‘Managing Infestations’). Small numbers of beetles developing within wood may continue to emerge for up to about five years. This is due to diminished suitability of the wood rather than from new infestation. Homeowners should be aware of this possibility.
Lyctids have less stringent moisture requirements than other types of powderpost beetles. Infestations can persist in wood with a moisture content as low as about eight percent, a common occurrence in indoor, temperature-controlled environments. However, in drier wood (less than 10% moisture) maturation of larvae is prolonged, due to declining starch content.
As noted earlier, lyctid beetles typically start emerging from wood within a year of processing. Thus, infestations usually are encountered in new homes or newly manufactured articles. In almost all cases, infestation results from wood that contained eggs or larvae at the time it was brought into the dwelling. This is significant because responsibility for treatment or replacement often resides with the supplier, manufacturer, or installer, rather than the homeowner. The infested article probably was constructed from wood that was improperly dried or stored. Although lyctids sometimes infest firewood, this is seldom the reason other materials become infested within a home.
Bostrichid powderpost beetles vary in size depending on the species. Most associated with wood products are reddish-brown to black beetles ranging in length from 1/8-1/4 inch. Compared to lyctids, bostrichids are less narrow-bodied and flattened, and the head is oriented downward, appearing somewhat “hooded” (Figure 3). Many species also have tiny, roughened, rasp-like protrusions behind the head, and some have a pair of projecting spines at the end of the body. Bostrichids create circular 1/8-1/4 inch holes in wood like other powderpost beetles. Female beetles have the unusual habit of boring directly into wood in order to lay eggs. These holes are devoid of powder. Conversely, holes formed by beetles upon completing their development are packed with powder. Wood powder produced by bostrichids is more meal-like than lyctid powder and tends to remain tightly packed in the holes and feeding galleries of the larvae.
Fig. 3: Bostrichid powderpost beetles have a ‘hood like’ appearance up by the head.
Bostricid powderpost beetles are more serious pests of hardwood than softwood. There is little risk to softwood framing within homes. Similar to lyctids, bostrichids usually attack newly processed woods with high starch and moisture content. Tropical hardwoods (including bamboo) are especially vulnerable to attack, which often occurs prior to importation. Although bostrichids seldom re-infest wood after the first generation emerges, extensive damage can occur the first year due to a high initial population and rapid development.
Anobiid powderpost beetles are convex, reddish to dark brown beetles capable of attacking both hardwoods and softwoods. They are sometimes confused with drugstore and cigarette beetles that also occur in homes but infest stored foods. The emergence holes are 1/16-1/8 inch. Rubbed between the fingers, the powder sifting from the holes and accumulating in small piles may feel gritty (although for a few species attacking hardwoods this is not the case). Unlike the powderpost beetles discussed previously, anobiids can seriously damage beams, joists, and other structural components of buildings. Anobiids prefer to infest moist wood. A 13-30% moisture content is required for development of the larvae. Consequently, infestations are most severe in damp crawl spaces, basements, garages, and unheated outbuildings (Figure 4). Buildings with central heating and cooling seldom have sufficient dampness to support beetle development in living areas or attics.
Fig. 4: Anobiid powderpost beetles infest damp areas such as crawl spaces.
Anobiid infestations occur throughout much of the country, but are more common in the southeastern and coastal states where humidity and temperature are high and crawl space construction is abundant. Unlike lyctids and bostrichids, anobiid powderpost beetles can digest the cellulose within wood, and are less dependent on starch and other nutrients that decline over time. This allows them to attack and infest wood regardless of age. In Europe, for example, some species of anobiids continue to infest wood in buildings that are centuries old. Larval development occurs slowly, exceeding 2-3 years if conditions are suboptimal. As a result, infestations are seldom obvious in buildings less than 10 years old. Although damage occurs slowly, the ability of emerging beetles to re-infest wood year after year can lead to serious problems requiring treatment and repair.
Emergence of adult anobiids generally occurs during the spring and summer months. In nature, they dwell in dead tree limbs or bark-free trunk scars. The adults are strong fliers and some are attracted to lights. Infestations within buildings may originate from infested lumber, firewood, or from beetles entering from outdoors.
Many similar-looking beetles that are not powderpost beetles may occur within buildings. It is important to know the difference to avoid confusion and ensure that costly treatments and repairs are not made unnecessarily. Definitive diagnosis usually requires confirmation by an entomologist or knowledgeable pest management professional. As noted previously, powderpost beetles are sometimes confused with other small brown or black beetles infesting stored food items (flour, cereal, grains, seeds, nuts, spices, pet/bird food, etc.). Examples include flour beetles, drugstore and cigarette beetles, weevils, and merchant/sawtoothed grain beetles. These pests typically occur near stored food items in kitchens, pantries, etc.
Another pest group often mistaken for powderpost beetles scavenge on surface molds associated with damp conditions. One of the most common is the foreign grain beetle (Figure 5). These beetles are small (about 1/16-inch long), brownish, and abundant, with large numbers often observed throughout the building. The key characteristic to look for in identifying this beetle is the presence of a slight projection or knob on each front corner of the shield-like segment directly behind the head. A microscope or other means of magnification is necessary to see this characteristic. Foreign grain beetles are one of a group of beetles that feed on molds and fungi growing on poorly seasoned lumber or wet plaster and wallboard. They often are a problem in newly built homes. When new homes are constructed, microscopic surface molds form on damp wood and sheetrock, which in turn attracts the beetles. In older homes, foreign grain beetles may be associated with plumbing leaks, condensation problems, or poor ventilation. None of the beetles in this category damage wood once the moisture condition is resolved, the surface molds disappear along with the beetles. (For more on this pest, see University of Kentucky Entomology Entfact-610).
Fig. 5: Foreign grain beetles are often mistaken for powderpost beetles (note the two small ‘knobs’ just behind the head).
Is the Infestation Active?
Powderpost beetle infestations often die out of their own accord. Therefore, it is important to know whether the infestation is active or inactive before taking action. Active infestations usually have powder that is the color of freshly sawed wood sifting from the exit holes. Compared to old, abandoned holes, new holes will not have taken on the weathered appearance of the surrounding wood (Figure 6). If flooring, cabinetry, etc. were previously stained, new emergence holes will have no traces of stain inside the holes. If accumulations of powder appear yellowed, caked, or covered with dust or debris, the damage is probably old. Careful observation may be required to distinguish new powder from powder dislodged out of old larval galleries by vibrations.
Fig. 6: Active versus inactive infestations. The former usually have fresh powder accompanying the emergence holes.
Another way to confirm that an infestation is active is to mark or seal any existing holes, sweep or vacuum up all powder, and recheck the wood for new holes and powder later on. Since most beetle emergence occurs in spring or summer, you may wish to wait until then to determine if new holes and fresh powder are present. This makes particular sense when attempting to determine whether an infestation is active during fall or winter.
Clients should know that there are a few different options for controlling powderpost beetles. Choosing the best approach depends on such factors as degree of damage, potential for re-infestation, and expense—both financial and emotional— that one is willing to bear. Powderpost beetles damage wood slowly. There is no need to act immediately for fear of risking the structural integrity of one’s home. A “wait and see” approach often makes the most sense, especially when there is uncertainty whether the infestation is active.
Prevention-Powderpost beetles, especially lyctids and bostrichids, typically enter buildings in lumber or manufactured articles, e.g. flooring, cabinetry, molding, paneling, furniture. Infestation occurs after wood is sawn into lumber and then sits in storage, or during transit and distribution. It is prudent for wood manufacturers to inspect incoming shipments for signs of beetles before they turn them into finished products. Wood that is suspect should not be used, especially if fresh emergence holes or powder is present. Many of the most serious infestations occur from using old lumber from a barn or woodpile to panel a room or build an addition.
Powderpost beetles lay their eggs only in bare, unfinished wood. Surfaces that are stained, varnished, painted or otherwise sealed are generally safe from future attack. Beetles emerging through such coatings were usually in the wood before the finish was applied. Although beetles emerging from finished wood can potentially re-infest by laying eggs in emergence holes, sealing the holes prevents this possibility.
Wood Replacement - Oftentimes, indications of beetle activity are limited to small sections of flooring or a few pieces of molding, trim, etc. The most efficient approach is often to remove and replace them, along with any boards or pieces directly adjacent as a precaution (Figure 7). This is especially true when the damage is due to lyctids or bostrichids. As noted, these powderpost beetles have a difficult time re-infesting wood after emerging indoors since, at that point, most surfaces are finished and starch and moisture is declining. When replacing sections of flooring, difficulties sometimes arise in matching the finish of the existing floor. If this is the case and the entire floor needs to be sanded and refinished, it is often prudent to wait at least six months in case more holes appear and additional boards need replacement.
Fig. 7: Replacing small sections of damaged wood can be an effective means of control.
Lethal Temperatures- Before wood is used for construction or manufacturing, most of the water is removed by air-drying or kiln drying. Kiln-dried lumber is heated for a period of hours to a temperature of about 125-140°F. This is sufficient to kill all stages of powderpost beetles that might be in the wood prior to heating. However, even wood that is properly kiln dried may become infested during subsequent storage and transit. The longer wood sits in a vulnerable condition, the greater the chance beetles will find and lay eggs on the lumber.
The pest control industry also uses heat to treat dwellings and furnishings for bed bugs. While it would be difficult to kill wood-boring beetles in ‘built in’ components like floors and cabinets, de-infestation of furniture and similar objects may be possible within a heat chamber. Pest control firms use stationary and portable heat chambers of various sizes. Temperatures employed or for powderpost beetles would be similar to those used for bed bugs (120-135°F), although exposure times might need to be longer, e.g., up to 24 hours, depending on wood thickness. Powderpost beetles can also be killed by placing smaller items such as wood carvings and picture frames in a deep freeze (0°F) for 3-7 days, again depending on wood thickness. For more on this topic, see University of Kentucky Entomology Entfact-640, Thermal Deinfestation of Household Items.
Moisture Control-Anobiid powderpost beetles in particular have high moisture requirements for survival. Wood moisture below 14 percent during spring and summer are generally unsuitable for development. Therefore, it is advisable to install a moisture barrier in damp crawl spaces that are infested. Covering the soil with polyethylene sheeting reduces movement of moisture into the substructure and reduces the threat of the infestation spreading upward into buildings. Other ways to lower wood moisture content in crawl spaces is to improve drainage and increase air circulation by installing foundation vents. Moisture meters utilized by pest control firms are handy tools for measuring the moisture content of wood and predicting the potential for infestation (Figure 8).
Fig. 8: Moisture meters are useful tools for predicting potential reinfestation.
Residual Insecticides - Various insecticides are used to treat beetle-infested wood. Insecticides known as borates are most widely used for this purpose. Borate sprays have the potential to penetrate and kill beetles within wood, as well as those entering or exiting the wood surface. Depth of penetration will depend on wood moisture content the damper the wood, the deeper the borates will penetrate. Two different formulations are used, Bora-Care and Tim-bor. Both products are virtually nontoxic and odorless.
For borates to penetrate the wood surface must be unfinished the spray will not penetrate paint, polyurethane, or other water repellent coatings. For this reason, the products have limited use for treating infestations within the living areas of homes. They are most often used for control and prevention of anobiid powderpost beetles infesting joists, beams, sills, studs, and other structural elements of buildings.
Borate sprays are sometimes used to treat beetle-infested hardwood floors, which first requires sanding to remove any finish. Besides being costly and disruptive, such treatments are seldom necessary since emerging lyctids and bostrichids are unlikely to re-infest. Additionally, in temperature-controlled buildings the moisture content of wood flooring tends to be around 10%. Borate penetration into wood this dry would be minimal and likely would have little effect on developing larvae.
Fumigation-Fumigation is an extreme and costly option for ridding a building of powderpost beetles. Homes undergoing fumigation are sealed with tarps and occupants must remain out for about three days. The concentration of gas is monitored and maintained at a specified level, and before being reoccupied, the building is ventilated.
Current fumigants containing sulfuryl fluoride are less effective against wood-boring beetles than those containing methyl bromide, which is no longer available. Consequently, de-infestation may not be successful. Structural fumigation may be warranted when infestations (typically of anobiids) have spread into walls, between floors, and other areas where access for surface treatment or wood removal is impractical. The best way to avoid such problems is early detection and one or more of the corrective actions mentioned earlier. Portable items such as furniture can be fumigated more effectively and at substantially lower cost than fumigating an entire building. Infested items are placed under tarps or in trailers or vaults to maintain gas concentration at the proper level. Some pest control companies offer this service to customers.
Discovering powderpost beetles can be very concerning to homeowners. It is important to diagnose the problem correctly in order to avoid unnecessary effort and expense. Confirmation of the type of beetle, and whether the infestation is active are crucial first steps. Other considerations include location and extent of the infestation, and the type, age, moisture content, and condition/surface finish of the wood. Since powderpost beetles damage wood slowly, take time to consider the options available for remediation.
CAUTION: Some pesticides mentioned in this publication may not be legal in your area of the country. If in doubt, please consult your local cooperative extension service or regulatory agency. Furthermore, ALWAYS READ AND FOLLOW LABEL DIRECTIONS FOR THE PRODUCT YOU ARE USING.
Review the images for tips on how to identify these predators.
Concavity between eyes, bearded face around beak-like mouthparts. Long legs with fleshy pads at end. Usually long, tapering abdomen. One pair of wings (as in all other flies) with stubby halteres in place of the hind pair.
Rarely seen because of their location in the soil or rotting wood. They tend to pupate near the soil surface so they can emerge more easily from their pupal cases