Trying to identify a beetle seen in Ontario, Canada… and its babies, or parasites?

Trying to identify a beetle seen in Ontario, Canada… and its babies, or parasites?

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I'm trying to identify a beetle I took video of in July (around 2010) in the Muskoka region of Ontario, Canada. Attached below is a still frame.

I've done some googling and was thinking this was a Milkweed Leaf Beetle because of the orange and black stripes. This beetle however has an interestingly marked green head, and Milkweed Leaf Beetles appear to only have a black head.

I'm especially curious to know if the smaller insects on this beetles back are its young, or some type of parasite.

I've just posted the original video to youtube. It's right here: Beetle Video

Thanks to pascal's answer, I looked at the genus Nicrophorus and agree that this is some member of that genus. (The spelling Necrophorus has been used in the past but is now deprecated.) The 60+ members of this genus are commonly known as burying beetles or sexton beetles from their behavior of burying dead small animals to serve as nourishment for their offspring.

However, instead of N. vespillo, I think the species might be N. tomentosus:

(Photo: Judy Gallagher via Wikimedia Commons)

The most distinguishing feature seems to be the green or gold hairs on the thorax as seen clearly in the large version of OP's photo. These hairs or setae Wikpedia mentions as separating N. tomentosus from other members of the genus. A common name for the species is "gold-necked carrion beetle". Two other photos of this species are here and here.

I think I agree with mgkrebbs that this is N. tomentosus but the members of this genus are all very similar to one another. The part of your question that inquires about the "smaller insects on this beetles back" is of interest. They are not insects, they are mites.

The behavior of these mites is called "phoresis" and there is a good illustrated article here about it. The mites are simply using the beetle for transportation to food. The beetle is better than the mites at finding dead animals and is able to fly. This species of mite has evolved the lifestyle of a "hitchhiker" on the beetle. They have therefore become dependent on the beetle, but they are not a parasite, because the beetle is not harmed. In fact, there may be some benefit to the beetle, which would make this a mutualistic relationship.

This is a beetle of the species Necrophorus vespillo (or a relative), very common beetles. It is parasitized by some mites. A similar picture as yours can be found on this page. I like it very much! We can see on the external page, that those little creatures are mites.

(Picture from wikimedia commons)


Striped skunks are stout little animals with stumpy legs. They have small heads, short, pointed snouts, and little black eyes. Their most distinctive feature is the white stripes that run along their backs and extend to the tips of their long, fluffy tails. Skunks usually grow between 50 and 80 cm in length and weigh just over 3 kg.

Spotted Skunks

While most people are all too familiar with striped skunks, the smaller and scarcer spotted skunk is less well known. Sometimes called polecats or civet cats, these pests are members of the weasel family. They share striped skunks’ familiar fluffy tails, black or brown colouring, and pure white markings, though their patterns look more like dots or streaks. This pest is also more likely to be seen around woodlands and forests, as they are less comfortable near people.

Spotted skunks are skilled at burrowing, tunneling up to a foot underground to make their dens. As these pests frequently choose to burrow underneath porches, decks, and sheds, they can weaken foundations. Spotted skunks will defend themselves and their young by spraying foul-smelling, sticky liquid. Even more pungent than striped skunks, these pests’ odours can linger in yards for up to four months.

Skunk Tracks

In basic shape and appearance, skunk tracks most closely resemble bear tracks, except they are much smaller. Like bears, skunks have a flat-footed walk, so the entire print makes an impression on the ground. This makes skunk track identification somewhat easier than picking out the prints of other, similar-sized animals. Skunk prints show five toes on all four feet. The long claws for digging on their front paws appear in tracks as small points in front of the toes. Large, rectangular heel pads on their back feet also have a second, smaller pad behind them that may appear as a single dot.

Although skunks do not hibernate in the winter, they are far less active and may stay in their dens for several weeks at a time. For this reason, seeing skunk tracks in the snow is a rare occurrence. They are sometimes confused with squirrel tracks, though squirrels only have four toes on their front feet. Muddy ground or fresh dirt disturbed by skunks as they dig for insects is the most likely to display their prints.

Habitat, Diet, Lifecycle


Distributed throughout the provinces, skunks are found as far north as the Northwest Territories and Nunavut. They live in farm fields, grasslands, forests, and urban areas. Although skunks are proficient diggers, they prefer to utilize the abandoned burrows of other animals instead of creating their own. In winter, skunks are very inactive and spend most of their time curled up inside their burrows until the arrival of spring.

Skunks in the City

Skunks are burrowing animals that, despite being timid, adapt surprisingly well to living among humans in urban areas. They are not skilled climbers, so homeowners don’t need to fear them getting into attics and chimneys. However, they will make dens under porches, decks, and sheds by digging as deep as a foot down. Canada is home to two species of skunks, the most familiar being the striped skunk found across the country. The other is the spotted skunk, which is found in the southern lower mainland of British Columbia. Other than the spotted skunk being slightly smaller and having a striped, more erratic pattern, the two species are very similar.

Daytime & Nighttime Behaviour

The nocturnal nature of skunks keep them mostly out of sight during daylight. Once they’ve settled on a property, the bulk of skunk damage comes from their digging up lawns in search of grubs and worms to eat. As opportunistic omnivores, they are also attracted to birdseed, pet food and garbage. It’s common for residents to smell skunk dens before ever seeing evidence of the animals. Signs to look for include holes 10 cm to 25 cm in diameter under buildings, decks, or wood piles.

Answering the question, “Where do skunks live?” is important for avoiding the dangers they pose. Skunks are known for spraying foul-smelling liquid as well as being capable of transmitting certain diseases. Due to this, it’s best for homeowners to trust the wildlife removal specialists at Orkin Canada to handle problem skunks.

Skunk Dens

While they prefer to use the abandoned holes of other burrowing pests, skunks may also opt to make their dens under decks, porches, and sheds. Skunk dens are used by adults when they give birth to young in the spring and also to avoid cold weather in the winter. Typically solitary pests, skunks can be drawn together during colder weather in these makeshift homes, sometimes with as many as 20 individuals living together. At times, these pests may even use rock heaps, wood piles, and crawl spaces under homes.

As opportunistic omnivores, skunks eat almost anything. In the wild, their diets include rodents, eggs, insects, worms, and plants. City-dwelling skunks help themselves to trash, fruits and vegetables from home gardens, grubs found in residential lawns, and small animals like mice and squirrels.

Life Cycle

Mating occurs in the early spring, and mother skunks give birth to litters ranging in size from two to six kittens. Young skunks are capable of spraying their defensive stench at little more than one week old and are completely weaned from their mothers after a couple months. Striped skunks can live up to three years in the wild.

Why do I have skunks

In the wild, skunks live in farm fields, grasslands, forests. They are proficient diggers, but they prefer to use the abandoned burrows of other animals instead of creating their own.

In urban settings, they have adapted to living near humans and raid trash cans, gardens, outdoor pet food, and compost piles for food.

Skunks eat almost anything. In the wild, their diets include rodents, eggs, insects, worms, and plants. City-dwelling skunks feed on trash, fruits and vegetables from home gardens, grubs found in residential lawns, and small animals like mice and squirrels.

How worried should I be about skunks

When threatened or surprised, skunks release a foul smelling spray so powerful it can cause skin irritation and blindness. The oily musk is notoriously hard to remove and the stench of the spray is potent for several days.

Skunks can also eat garden fruit and vegetables, scatter trash everywhere, dig up lawns in search of worms, and transmit the rabies virus. To have a skunk removed from your property safely and humanely, you need a professional pest control service.

How can I prevent skunks invading

Look out for conical holes in the soil, Check for piles of dirt pushed out, Keep all trash cans secure, Remove bird feeders and pet food, Install fences buried into the ground, Secure gaps under decks and porches

Can a baby skunk spray

While it can take several weeks for newborns to be active, their ability to spray foul-smelling liquid develops within their first few weeks of life. Still, skunks only spray other animals and people when they sense threats. Since newborn skunks rarely leave their dens before they are weaned from their mothers, encounters with the young pests are infrequent.

Do skunks climb

Despite its curious nature, the striped skunk isn’t very good at climbing. Therefore, unlike squirrels and raccoons, they cannot easily infiltrate attics and chimneys. Instead, their stocky bodies are built for digging and catching bugs with tails that are ill equipped for balancing and climbing. Short, strong legs and tough claws help striped skunks scrape though dirt in search of food like grubs, earthworms, and insects. These burrowing animals inhabit clearings, pastures, fields, and other areas where the ability to climb isn’t particularly useful.

Spotted skunks, on the other hand, are smaller, lighter, and more agile than their striped cousins. Their claws have adapted to provide enhanced climbing abilities, which make them more likely to den in attics and chimneys. Spotted skunks climb up trees to eat honey from beehives and scurry up straw bales in search of rodents. Homeowners often despise their presence, as these climbing skunks can get into garbage cans just as easily as raccoons or squirrels.

Different definitions of differentiability

In our lecture we have defined differentiability as follows:

$f:Msubseteqmathbb^m omathbb^n$ is differentiable at point $a$ if $a$ is an interior point of $M$ and there exists a $n imes m$ matrix $A$ such that: $ limlimits_frac=0. $

In a book which I read and here on MSE I frequently came across the following alternative definition:

$f:Msubseteqmathbb^m omathbb^n$ is differentiable at point $a$ if $a$ is an interior point of $M$ , there exists a $n imes m$ matrix $A$ , a function $varphi(x)$ which is defined on a neighborhood of $ with the property $limlimits_ frac=0$ and a neighborhood $N_a$ of $a$ such that for all $xin N_a$ : $ f(x)=f(a)+A(x-a)+varphi(x-a). $

So far I have mostly worked with the first definition. To me it seems to be easier to handle differentiability-problems with this definition.

However, I am wondering what the reasons might be to apply the second one? Maybe there are some good reasons from the vantage point of a more experienced mathematician? I would be happy to hear some opinions on that.


Systematic monitoring of pest populations, weather conditions, plant health and disease symptoms are critical components of an IPM program. This will allow early detection of pest populations, before they become too big. The accurate and timely diagnosis of a plant problem is important if the most effective control measures are to be selected and implemented. This, in turn, will minimize the damage to the plant's yield and aesthetic value. This is particularly true with a specialty crop, when you cannot be sure of all the pests that are likely to attack it or whether chemical controls will be available.

A. Scouting

Crop monitoring in IPM is commonly referred to as scouting. Scouting is the routine, systematic inspection of a field to monitor crop development, plant health, pests and beneficial organisms. Routine inspection is important, as this allows for observations of how pest populations change throughout the growing season, which can have important impacts on control decisions. This can be done by professional scouts, the grower or an experienced farm worker.

Before beginning a scouting program, review the potential pests identified in initial research. Learn to identify life stages and damage caused by the likely diseases and insects and understand their biology and life cycle. Learn to recognize beneficial and harmless insects. If previous crops planted in the field may share pests with the specialty crop, use historical data to identify hot spots and previous problems. Become familiar with the crop's normal appearance and growth pattern. This helps in identifying any abnormalities.

The following are some general tips on scouting taken from OMAFRA's CropIPM Resource and other publications. Consult the OMAFRA website for more detailed information on scouting.

  • Assemble your scouting tools and carry them with you into the field:
    • a 16-20x hand lens
    • traps
    • collection bags and vials
    • field maps
    • flag tape
    • shovel or sturdy trowel
    • pocket knife
    • scouting forms and record sheets
    • soil corers and a bucket can be useful if sampling for nutrients or nematodes
    • Does the plant show wilt, dieback or discoloration
    • Moulds, mildews, mushrooms and other spore producing structures these are the signs of fungi. Look for the presence of a cloudy fluid (bacterial ooze) which might indicate an infectious disease.
    • Inspect the plant(s) closely for webbing, cast skins, excrement, and other signs of insects, as well as for the pest themselves. Many insects, such as aphids, caterpillars and beetles can easily be seen on plants. Others such as maggots are not likely to be seen until damage is done. If these pests have been a problem in the past, preventive measures will be required
    • How are symptoms distributed on the plant, and on other plants in the area which non-crop species are affected (if any)
    • Don't forget that many pest problems occur out of sight, under the soil surface. It may be necessary to dig up a plant to look for root damage or soil insects.
    • Bear in mind that weather conditions, site, soil conditions and cultural practices such as chemical use, fertilizer application, and watering practices will also affect plant growth. Often, it is a combination of factors that create the problem. Plants under stress from poor environmental conditions, for example, are more susceptible to infectious diseases and pests.
    • the stage of crop development
    • disease severity
    • population levels of insect pests and beneficials
    • damage observed
    • record the location of damage on a field map
    • rainfall amounts, daily highs and lows, and weather events
    • pesticides applied and other control measures used
    • Divide large areas into sample blocks.
    • Walk in a W or zig-zag pattern across the field to collect samples from a representative area.
    • Look away from the plant when you take samples of leaves and fruit, etc., otherwise you will tend to choose damaged leaves or fruit and bias the sample

    B. Diagnosis

    Accurate diagnosis of the pest causing a problem is critical to effective and cost efficient integrated pest management. Treating for the wrong pest costs a grower time and money, and a delay in treating the correct pest can lead to crop loss. Insects, diseases and abiotic damage can all be mistaken for one another. For example, mites and leafhoppers can both cause bronzing and distortion of hops leaves, as can nutrient deficiencies. Brittle and distorted leaves can also occur as leaves die from some diseases. Consequently it is important to remember that for specialty crops in particular, it will be easy to misidentify pests.

    By following the steps outlined in the previous sections and routinely monitoring for likely pests, growers should be able to recognize emerging pest problems in new crops. However, growers of specialty crops are at a disadvantage because their crop is new to Ontario and there is no established body of information on the major pests, as there is for larger acreage crops.

    There is a wide array of resources available to aid in identifying pests. Some of these include:

      , an online resource aimed at identifying pests of major horticultural crops in Ontario. Although targeted at larger acreage crops, there are many photos of pests that will also attack specialty crops. Note that this resource may mention pesticides that are not registered on specialty crops. is an online site with a large collection of photos of North American insects.
  • The American Phytopathological Society publishes a series of books with detailed plant disease information for specific groups of crops (e.g. Compendium of Brassica Diseases, Compendium of Lettuce Diseases, etc.). They can be found at their on-line store, at many university bookstores or at various online booksellers websites.
  • Some useful books include:
    • Howard, R.J., Garland, J.A. and Seaman, W.L. 1994. "Diseases and Pests of Vegetable Crops in Canada". Canada Phytopathological Society.
    • Koike, S.T., Gladders, P. and Paulus, A.O. 2006. Vegetable Diseases: A Color Handbook. Academic Press.
    • Datnoff, L.E., Elmer, W.H. and Huber, D.M. 2007. Mineral Nutrition and Plant Disease. American Phytopathological Society.
    • Marshall, S.A. 2006. Insects: Their Natural History and Diversity. A Photographic Guide to Insects of Eastern North America. Firefly Books.
    • OMAFRA CropIPM's Beneficials Gallery for Apples, Grapes and Tender Fruit.
    • The Great Lakes Vegetable Working Group has produced an excellent flyer and video on identifying Natural Enemies of Vegetable Crops.
    • Cornell University has an online guide to natural enemies.

    Despite the array of resources available, it can still be difficult for growers of many crops, especially new crops, to accurately identify a pest. Where there is significant damage and a pest cannot be identified, professional help may be required. Places to seek help include:

    • Laboratories for Leaf Analysis
    • Laboratories for Soil Analysis
    • University of Guelph Pest Diagnostic Clinic
    • Local agrologists and crop consultants
    • OMAFRA specialists

    Black widow spider bite symptoms usually start 20 minutes to one hour following the bite, and can include pain, though not all people experience pain. Other symptoms include muscle cramps and spasms, abdominal pain, tremors, weakness, or a rise in blood pressure. Seek medical attention immediately. Treatment includes antivenin (which counteracts the spider toxin) and pain medications if necessary.

    The round goby&rsquos aggressive habits and rapid spread have had serious impacts on native species.

    • The fish compete with and prey on native bottom-dwelling fish such as mottled sculpin (Cottus bairdii) and logperch (Percina caprodes). Round goby also threaten several species at risk in the Great Lakes Basin, including the northern madtom (Noturus stigmosus), the eastern sand darter (Ammocrypta pellucida), and several species of freshwater mussels.
    • Round goby have reduced populations of sport fish by eating their eggs and young, and competing for food sources.
    • Researchers believe the round goby is linked to outbreaks of botulism type E in Great Lakes fish and fish- eating birds. The disease is caused by a toxin that may be passed from zebra mussels, to goby, to birds, resulting in large die-offs of fish and birds.

    To prevent the spread of this invasive species, the Ontario government has banned the possession of live round goby and the use of round goby as a baitfish.

    Small, bottom-dwelling round goby. Photo: David Copplestone, MNR

    1 Answer 1

    This is a very, very tough question. It is obvious that for any graph $G$ with $n$ edges the number of spanning trees $t(G)$ does not exceed $2^n$ (each edge is either included in or excluded from a subtree this is also the upper bound of the number of connected subgraphs of $G$ ). We can somewhat improve this - if $G$ has $m$ vertices ( $m leqslant n+1$ ) then we have $ t(G) leqslant inom < 2^n , $ since we need to choose $m-1$ edges out of $n$ (not arbitrarily, of course).

    It is a bit easier for the planar graphs but you are correct that the exact formula is not known. I will say more, there is no exact formula even for such a "simple" planar graph as $Z_$ , which represents $n imes n$ rectangular lattice.

    However, there are a few upper and lower bounds, most of them pretty complicated. I suspect there should be an elementary proof for the following conjecture.

    Conjecture. For any finite connected planar graph $G$ with $n$ edges we have $ t(G) < au^n, $ where $ au$ is. say, $1.8$ .

    Perhaps I am a bit optimistic about 1.8 but there has to be some value of $ au < 2$ for which an elementary proof exists. I am actually doing some low-tech research into that area right now.

    An example: for large values of $n$ it is known that $t(Z_)$ is pretty close to $ au^n$ , where $ au = e^ <2C/pi>approx 1.7916. $ , where $C$ is the so-called Catalan constant $ C = 1 - 1/3^2 + 1/5^2 - 1/7^2 pm . $

    Identifying Juvenile Birds

    The first step in determining what species of young bird you see is to be sure it is, in fact, a juvenile bird. Some adult birds look similar to fledglings, but these characteristics can help you be certain that you are seeing juvenile birds.

    • Bill Size: Juvenile birds often have bills that seem proportionally too large for their head. This is because their heads have not fully grown and their feathers are not yet covering the edges of the bill, making it seem larger.
    • Feather Length: Young birds have not grown full flight feathers, and the feathers on their wings and tail will be noticeably stubbier than on adult birds. The feathers on their breast, flanks, and abdomen may also seem fluffier and less organized than those of adult birds, not only because they're not fully grown, but also because young birds do not preen as effectively as adults. Some feathers may be so underdeveloped that the birds even show bare skin, especially on the face.
    • Color: Many juvenile birds have drab, dull plumage similar to that of an adult female. As they molt, their feathers may have additional speckles, buff edges, or other disorganized colors that help camouflage them until they can fly skillfully.
    • Eye Size: Very young fledglings and nestlings have bulging eyes that seem too big for their head. This should not be strongly noticeable in birds that are ready to leave the nest, but if the birds were displaced very early their eye size can indicate their youth.
    • Behavior: Young birds often try to draw the attention of their parents. They may beg for food or flutter their wings, especially when near adults. They may also be uncertain in flight or may visit feeders but seem unsure of how to eat what is offered. It should be noted, however, that many juvenile behaviors, including fluttering and begging, are similar to the courtship of adult birds. Behavior alone is not a sure indication of whether or not a bird is juvenile, but it can be a valuable clue.

    If a bird exhibits several of these characteristics, it is likely a young bird. The next step for most birders, then, is to determine just what species of bird it is.

    Keeping an Eye on Tench, an Invasive Fish That’s Crept Into the Great Lakes

    Several dozen fish called tench swam against a gentle current flowing in blue plastic bins covered by a tarp and chicken wire (to keep out raccoons). The fish—which drifted above sand or rocks or nothing at all—had been plucked from the wild to live strange new lives in a wooded corner of McGill University’s Gault Nature Reserve near Montreal. It was all part of an experiment conducted last fall by biologist Sunci Avlijas to see whether the tench, an invasive species from Europe and Asia, might reveal their preferred habitats. The goal: to learn whether the Great Lakes would fit the fish’s bill.

    First brought to Quebec in the 1980s, tench, with their red eyes and green scales, have spent the past 30 years infiltrating the St. Lawrence River. A month after Avlijas wrapped up her research, this past September, tench were found in Lake Ontario for the first time, having pushed past the locks and dams meant to contain the species in the river. Tench are now officially among the ranks of hundreds of Great Lakes invaders. But it remains unknown if this fish will flourish and wreak havoc, as the zebra mussel and sea lamprey have.

    Adult tench can grow as long as 27 inches, a size that would make them difficult prey in Great Lake ecosystems. And as bottom feeders that munch on large invertebrates like mollusks, they might compete with native fish like yellow perch for access to food. Stomach dissections have shown tench also eat fish eggs, which could put a dent into certain local populations. To boot, the fish are known to carry multiple parasites.

    It’s a worry, but not a direct threat just yet. Avlijas emphasizes that the Lake Ontario discovery this past October doesn’t prove the fish are well established at this point in time. “But it’s likely we’ll catch more in the coming years,” she warns. And depending on how many more, Tinca tinca could end up being a major problem for the Great Lakes.

    Predicting the scale of this invasion has been the focus of Avlijas’s graduate career. She’s observed tench in other nonnative habitats, such as South Africa, and traced the species’ global journeys back to the 1500s, when fishmongers began carting the fish around Europe. Today the species lives on every continent but Antarctica. Even so, tench don’t take off in every habitat.

    The fish’s long history of introductions to the United States, for instance, has been hit-and-miss. Stocked in watersheds from Maryland to Oregon as a sport fish by the U.S. Fish Commission in the late 1800s, carried live from Italy to California in 1922, and brought to many other states (including Illinois and Ohio in 1891), tench have either quickly died out or thrived.

    “It’s a really interesting species because it has such a varied effect,” Avlijas says. “In some places it doesn’t manage to establish in other places it booms.”

    Booming is what happened in Quebec. A farmer transported 30 of the fish to the province in 1986 with the idea of establishing an aquaculture operation. No one was buying, so he drained his ponds five years later. Tench, however, have an impressive ability to survive in low-oxygen conditions with little water—all they need is a few inches to splash through. They floundered into the Richelieu River, a tributary of the St. Lawrence, and spread. Fishers participating in an early detection program in nearby Lake St. Pierre went from catching no tench in 2004 to catching nearly 10,000 in 2014.

    “It was predictable that as tench became more abundant they were going to spread further and further,” says Anthony Ricciardi, an invasive species biologist at McGill University who has coauthored papers with Avlijas. But for Ricciardi, tench are just another symptom of a much larger problem.

    Around 200 invasive species currently occupy the Great Lakes. Most have found their way to the freshwater ecosystem via human folly, such as through lax ballast water regulations or intentional bait releases. According to Ricciardi and other scientists, prevention is the best strategy when it comes to biological invasions, and policymakers should follow a protocol of early detection and rapid response.

    Additional information

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