Ask The Entomologist

Ask The Entomologist: What’s this bug in my breakfast?

“This guy and its buddy were both about 5 mm (1/5 inch) long, in my Malt-O-Meal.”

Excellent question, and an attractive little fellow it is.
This furry worm-like beastie is a larder beetle larva, a member of family Dermestidae.

If you’ve ever watched a criminal mystery program on television, you’ve probably seen these insects’ relatives make an appearance with forensic entomologists. Dermestid beetles are often used to clean meat off bones, whether for criminal investigations or by folks who prepare skull mounts. They’re better than chemical treatments, as they leave no markings on the bones themselves, and can be stopped before they destroy the connective tissues holding the creature together.

While entomologists call these things dermestid beetles, there’s a variety of names for them, depending on the species and what they like to eat. Often the bone-cleaning ones are called hide beetles” or “skin beetles The household stored-product pest names you might be familiar with are larder beetles or carpet beetles. As these names imply, there’s quite a bit of variation in what these insects eat.

These insects are survivors. Many species of dermestid beetle occupy some of the worst, least-tasty carcasses out there… These beetles tend to come late to bodies, after most of the good juicy bits have been eaten or have spoiled. I’ve found dermestid larvae between dry ocean fish vertebrae, inside a variety of mammal skulls, as well as in the dried out bodies of little things like mice, songbirds and lizards.

While some species can be helpful at times, most can become pests, especially to taxidermists or fur preparers. It’s an absolute nightmare trying to get dermestid beetles out of museum collections – they’re happy to eat just about anything dry and once living – aged fabrics and hide clothing, pressed plant specimens in herbariums, as well as taxidermied animals (skins as well as hairs or feathers). They don’t discriminate between vertebrates and invertebrates either – dermestid beetles are quite happy to eat pinned insect collections, too.

This three-color band pattern is very common in dermestid beetles.
This particular individual is a true larder beetle, found in my sack of short-grain sticky rice.

Some dermestids have found that sacks of grain are to their liking as well. Here’s a stowaway I found in one of my sacks of rice recently – a diet much more similar to that of your malt-o-meal beetle. It stands to reason, of course – they’re the same species, Dermestes lardarius.

Should you have problems with these in your own home, both Colorado State University and The Ohio State University have made nice informational sheets on how to control larder beetles and other dermestids.
CSU’s dermestid info & control sheet & OSU’s dermestid info & control sheet.
If they should get into your emergency food cache, though, don’t worry. They’re good eating.

And a closeup – this adult larder beetle is just a little bit bigger than the larva in the ID request photo.
Just over 1/4th inch, as opposed to 1/5th of an inch.

Ask The Entomologist

Ask the Entomologist: Ladybugs – which types bite?

First off, this is an excellent question.
All ladybeetles have jaws and the ability to bite, but some certainly seem to do so more often.

I’m fond of this question for more than that, though.
I got my start in entomology as a highschooler in South Dakota. Dr. Louis Hesler, a USDA lab scientist who specialized on ladybeetles took me under his wing, and helped me learn to identify them. I specialized in dissecting and identifying tiny ladybeetle species, often less than 1/10th of an inch long. That was the first time in my life that I felt I was doing work that couldn’t be easily replaced, and it was an addictive feeling.

If you have ladybeetles in your home, and have been bitten by them, I’d expect them to be Multicolored Asian Ladybeetles. Other ladybeetles are quite capable of biting, too, even if they don’t do so terribly often.
It’s more a question of what kind of ladybeetles we regularly encounter in our homes.

This past autumn I saw just over a dozen species of ladybeetles around our place… and I wasn’t searching for them. For comparison, South Dakota is currently known to have 80 species of ladybeetles. Chances are good that Montana has a similar or higher number. Despite all the ladybeetle species we had outdoors this summer, the only species I’ve seen in our home this winter is the Multicolored Asian Ladybeetle.

Why are these beetles in our homes? To avoid the cold weather.
While most ladybeetles need to avoid freezing to survive winter, not all do so in the same way.

European ladybeetles, such as the Seven-Spotted Ladybird Beetle (now common in North America as well) often overwinter in leaf litter. New World ladybeetles, such as the Convergent Ladybeetle, tend to overwinter inside rotting trees, much like Cluster Flies further from human structures do. Smaller ladybeetles are known to overwinter inside ant burrows, feeding on their larvae through the winter.

The Multicolored Asian Ladybeetle, has a different history, though. This species has lived alongside soybean farming for ages – the soybean was domesticated in the 11th Century BC. The Asian Ladybeetle’s ancestors overwintered in barns after the soybean harvests, and its descendants seek out shelter in human-made structures as well… It is this behavior that brings them into conflict with humans more than other species of ladybeetle.

Not all entomologists think that Asian Ladybeetles are likely to bite.
This write-up found that only about 1/4 of Asian Ladybeetles bit the author when given the opportunity… When not removed from his hands after they began biting, the Asian Ladybeetles happily feed on him for about a half hour. I suspect few people besides entomologists have personally experienced this phenomenon, however. One can see how similar behavior on fruits can quickly make these into pests.

How can I prevent the Asian Ladybeetles from invading my home in the winter?
Well, I can tell you what doesn’t work, and what ostensibly should work.

Putting up “Ladybug Houses” will not work at all. These beetles aren’t stupid – they can tell it’s warmer in your home than in the ladybug house, so your home will be their clear preference for winter quarters.

It’s theoretically possible to caulk your house so well that insects won’t be able to get inside. In practice, I don’t think this is viable at all. Good luck getting all those 1/16th inch cracks closed! There will always be a few tiny gaps that you miss, and the insects will invite themselves in to the warmth.

If you feel the need to remove your ladybeetle infestation, I’d suggest vacuuming. With a good suction attachment, you’ll be able to remove the Asian Ladybeetles without smushing them and making stains. I’d suggest emptying the vacuum bag promptly, or they’ll crawl out and continue on their merry way. Purdue Extension advocates using socks when vacuuming bugs.

Vacuuming them up can also be a wise idea if you’ve got a dog who likes to eat ladybeetles. Consuming sufficiently large quantities of ladybeetles, regardless of the species, can make your pets sick. But, as Paracelsus said, “The dose makes the poison”. It takes a special dog to eat one ladybeetle and decide to follow it up with fifteen more. I suspect your beasties may be a bit more discerning.

An excerpt from my mentor’s poster of the Ladybeetles of South Dakota.
I’ve observed many of these species here in Montana as well.

Community, Wildlife

Winter changes voles’ moods, too.

As the seasons wear on, and we begin another year with our movements restricted by Covid19, it’s easy to see cabin fever creeping up on folks. People who wouldn’t ordinarily have conflict, begin to. Those who started out with strife and high tempers can’t be said to have improved. This plight turns my mind to the voles, and how much better they handle winter than us humans.

Voles are kin of mice – not true mice, biologists will tell you, as they’re more closely related to muskrats and lemmings, but functionally they behave much like true mice. Voles can be distinguished from mice by having shorter & blunter snouts, smaller eyes and ears, shorter tails, and classically bad teeth. To me their teeth bring British films to mind – Monty Python & The Holy Grail, for example.

This handsome gentleman made the mistake of trying to fight the little Pomeranian mouser.
He reared up on his hind legs, squeaking menacingly… and the other Pomeranian grabbed him from behind.

Voles, genus Microtus, are territorial little beasties. While primarily herbivorous, voles do appreciate a varied diet, and some are fierce grasshopper hunters. Like many small mammals, voles seem to believe that one should encourage annoying neighbors to live elsewhere by devouring their children (I’m rather glad most humans don’t espouse this belief). Sensible little creatures, voles will readily dine on carrion, and aren’t opposed to eating dead (or mostly dead) kin caught in traps.

Largely solitary-living, voles are ready to fight and kill in defense of their sovereignty in summer. This is particularly true for actively reproductive females, who tolerate no other reproductive female trespassers.

However, vole behaviors change with the seasons. Unlike you or I, voles become more sociable and tolerant of others during the cold of winter. Instead of eviscerating that annoying cousin, as their first inclination would be in the summer, when wearing winter’s brain, voles instead perceive that nuisance relatives could be of utility and might generate enough warmth to be worth keeping around.

Voles realize that they’ll only get through the cold harshness of winter together. You see, voles don’t make burrows deep enough to avoid the frost, and thus need the warmth of others to survive. And so they build wintertime nests of dry grass, and pile within those nests, keeping warm by shared bodyheat.

The importance of food:
But one can not survive on warmth alone – voles need to eat throughout the winter months as well.

To do this, they build tunnels leading away from their dry grass nests, and feed on plantstuffs wherever they can. This is the main reason why voles become pests in winter months. For such small animals, they can be quite destructive – they’re quite capable of girdling trees, if it’s what it takes for them to get food.

While this allows foraging, voles only forage a few at a time – always leaving a number of voles behind, sleeping in the nest to keep it warm. Once those voles that are foraging have returned, it will be others’ time to seek food.

Here’s a vole foraging runway, partly uncovered by melting snow. These paths are about 1.5 inches wide. Note that the tunnel branches like a “Y” at the top of the image.

Vole control:
The best means of controlling voles is by predators. Garter snakes will contribute, as will hawks, but for our geographic area, our various weasels are likely the best means of controlling voles. In the absence of good weasels, a cat or dog with aspirations of becoming a good mouser will be helpful as well – and oh, the joy if they happen to find the winter nest full of scrumptious voles.

In the absence of total control by predators, ringing the bases of trees you want to protect (either with wire hardware cloth or with protective plastic sheathing) is a wise idea. Regardless of what you pick to protect your plants, be sure to bury it 4-6 inches deep, so that voles will be less likely to tunnel beneath it. Reducing groundcover around plants you want to protect is a good idea as well – the voles won’t place their foraging tunnels across much bare ground.

If you’d like to take a more active approach, the thaw has been sufficient for me to find vole trails with little difficulty. Follow the trails long enough and you’ll discover their winter nests, little edifices of dry grass, about 8 inches across. Find one of the nests and you may well make a little dog’s day.

Ask The Entomologist, Community

Why are there flies in my house? There’s snow outside!

If your home is anything like ours, it has had an abundance of flies lately. You may ask yourselves “why now?” – after all, it’s snowy out, and there can’t be much food for them. Shouldn’t they die with the cold like everything else?

You’d be entirely right in thinking so. Regardless of the type of fly, most of the good food sources are rather scarce this time of year, and the cold kills many. However, insects are just as uninterested in freezing to death as we are. Most of these gathered indoor flies are trying to avoid that particular fate.

My Mother-in-Law’s elegant, clear sticky traps, thoroughly filled with Cluster Flies and Fungus Gnats.

While we see many house flies, flesh flies, and blow flies in the summer, they aren’t the primary species to invade our homes in the winter (though I’ve met a few of each overwintering inside my home).

The vast majority of our new fly guests are a different group entirely – the Cluster Flies. Until quite recently, the Cluster Flies were grouped as a special sort of blowfly, but just over a year ago, they were given their own scientific family name, Polleniidae.

Cluster Flies get their name from their habit of gathering in large groups, often in windows. Some try to stay warm outdoors, nestled deep inside rotting tree trunks. More sensible ones move inside with us to stay warm and survive the winter. Cluster Flies don’t want anything to do with your food, plants, or pets – they’re just here to avoid freezing.

Eternal optimists, Cluster Flies often come out on warmer days, and try to find their way outside.
Thus the accumulation of dead ones on your windowsills when weather turns cold again.

It’s this habit of moving inside for the winter that is thought to have introduced Cluster Flies to the New World. You see, the Cluster Flies we have now aren’t North American natives. No. They’re thought to have sailed over from the Old World with some of the first European colonists.

Back when European countries were busy sending ships to build colonies in the New World, they brought many unintentional stowaways with them. Many of these scalawags are with us today, for better or worse. In this story, we care about two such emigrants. Earthworms (especially the Green Worm) and Cluster Flies.

It’s thought that earthworms were transported across the Atlantic in ships’ ballast. Meanwhile, some Cluster Flies took refuge from bad weather inside the ships themselves, just like they’re doing in our homes this winter, and so found their way to America as well.

Earthworms flourished when ships made landfall. Many of the formerly-glaciated parts of North America no longer had earthworms, and were ripe for Lumbricid conquest. The spread of earthworms, in turn, opened up North America to the spread of Cluster Flies. Both spread like wildfire, and now can be found all over our continent.

Why are earthworms important to Cluster Flies? You see, Cluster Flies are specialist parasites. Their maggots feed almost exclusively on earthworms. Mother Cluster Flies sensibly lay their little ones near earthworm burrows, and the newly-hatched maggots then see about journeying into earthworm burrows. There they lurk in ambush, waiting for a worm to pass by.

Thinking of tiny maggots catching hold of vast earthworms with their mouth-hooks as the worm passes by very much brings scenes of Frank Herbert’s “Dune” to my mind. I like to imagine the tiny Cluster Fly maggots singing this song as they hunt their earthworm prey, and carve their way inside.

Our friendly, local Cluster Fly – Pollenia pediculata.
As you can see, they’re a bit larger and hairier than our common houseflies, as well as easier to catch.

Because of their worm-based diet, Cluster Flies are actually remarkably clean compared to other flies with carrion- or dung-based diets. While you may not appreciate Cluster Flies’ presence, at least they will not spread disease.

Additionally, both my dog and I can attest to their superb flavor.

Ask The Entomologist, Community

Are there bugs in your mail?

I recently started working for the United States Postal Service, and, while I’ve been seeing quite a few bugs lately, few are the kind I like. While I’m not terribly fond of them, the sheer numbers these bugs occur in has been very impressive.

Mercifully, with elections past, there’s been a sizeable reduction in the numbers of incoming bugs in our P.O. boxes.

I’m talking about union bugs, specifically printers’ union bugs. These minuscule beasties seem to be on well more than half of our political junk mail this season! Here’s some fine examples of the species:

These strange ink-based critters colonize almost all publications that come out of unionized printing presses.

If you’ll notice, there’s a certain bias in the political affiliation of these bugs. At present, almost all Democrat-leaning political flyers are published in unionized print shops. Republican-leaning political flyers, on the other hand, are seldom published in unionized print shops, and most lack union bugs.

Republican flyer, lacking the Union Bug

This trend doesn’t necessarily hold constant across the country, though. Nor has it held constant over time – unions used to be strongly supported by the right, as a way that capitalism led to better worker conditions. And, alas, the presence of the union bug is no longer as indicative of an entirely union-made product as it once was…

Due to prevalent local political sentiments, certain political flyers have been disguising themselves to sneak their messages into new homes. Take a look at this piece of political mail – at first glance, you’d assume that LR-130 is opposed to the Second Amendment.

But look closer!
A union bug. This indicates a union press was used, and the flyer in question was most likely published by a left-leaning group. When we examine the bones of this legislation, LR-130 is actually in favor of the Second Amendment.

Cleverly camouflaged flyers and a fair bit of funding led to a surprisingly close vote on LR-130. It’s important to be well-informed on what the issues we’re voting on actually are – legislation and flyers rarely aim to be straightforward.

Mercifully, while pests of a sort, political flyers do not reproduce, unlike invasive insects. Personally, I’m rather grateful that we only have to deal with this volume of political propaganda once every four years.

Ask The Entomologist

Pine Bark Beetles and Fire Risk

The dense smoke currently hanging over our part of the country has had me thinking about beetles. Why beetles, you say? Pine bark beetles and relatives (genus Dendroctonus) are notorious for killing large stands of coniferous trees (Fir, Larch, Pine, etc.) – even their scientific name translates to “tree killer”.

As time goes by and environmental stressors increase, we’re seeing more and more tree die-offs related to these bark beetles. Death by bark beetle can triple the rate at which trees go up in flames. It’s not fair to put all the blame on the beetles, though – tree death is ultimately caused by infection from the fungi that the beetles spread. The one bright side of how destructive these beetles and fungi are is that they have been well studied. As a result, there are many ways of controlling their infestations.

Douglas-Fir Beetles I found under bark while splitting some Douglas Fir wood.
Note the “galleries” (tunnels) they’ve made – many bark beetles can be identified by the shape of their galleries.

The most effective way we can control pine bark beetles on our own is by good management of our forest resources. Keep tree stands resistant to pine bark beetles by thinning trees to a healthy density – beetles are most likely to become a problem in over-crowded woods. Beetle damage will become evident by “boring dust” – spots of reddish sawdusty powder along the trunk, and “pitch tubes” – globs of resin the tree has pushed out, trying to stop a beetle’s tunneling (red pitch tubes likely indicate infestation, while yellow ones often indicate successful defense).

Remove stressed, fire-damaged, and wind-thrown trees. Promptly clean up fallen timber. Damaged and downed trees are excellent places for pine bark beetles to reproduce, and should be removed before new beetles emerge! Where one beetle feeds and reproduces, there will soon be more – pine bark beetles attract each other to damaged trees by releasing aggregation pheromones.

A close-up of three Douglas-Fir Beetles – they have since been executed for their crimes.

My favorite method of control involves removing the pine bark beetles’ symbiotic fungi. Without these fungi, most of the beetles can’t reproduce well. Because it’s not practical to directly remove fungi from beetles in the wild, scientists have raised pine bark beetles in captivity. These captive-raised beetles can be inoculated with special aggressive fungi which can outcompete and kill the fungi that wild pine bark beetles carry. The thought is that captive beetles could be released and will interact with wild beetles, spreading their different fungi like a disease. The new fungus will prevent beetle reproduction and thus stop small infestations from becoming large and economically devastating ones.

Unfortunately, beetle-delivered fungal control treatments aren’t ready for public use yet – ask your Forest Service folks what beetle controls they are researching and testing! If you’re particularly concerned about pine bark beetle infestation, they may be able to use chemical measures like anti-aggregation MCH pheromone to lessen the risk.

Have you been seeing signs of pine bark beetle damage near your home?

Ask The Entomologist

Wasp control

I’d wanted to talk about how to read wasp body language this week, but that’ll be postponed. I couldn’t persuade any individuals to do threat displays this week – all live wasps were well-mannered, despite extreme invasion of their personal space.

Most of the wasps I’ve seen around Trego are Polistes paper wasps. We have two main species here – the invasive European Paper Wasp (Polistes dominula) and the native Golden Paper Wasp (Polistes aurifer). In our area, Golden Paper Wasps peak in July, while the European Paper Wasps peak in August. While both are still around, I’ve been seeing far more European Paper Wasps lately.

The European Paper Wasp is rather special, in that it doesn’t mind reusing old nests from last year and making them bigger. Because of this, they often reach a larger colony size faster than their native wasp competitors can. As such, these are likely to be most of the problem paper wasp nests you come across.

The best bait for trapping wasps will vary by season. My neighbors have been having great success baiting their wasp traps with scallop and chicken… this means that the wasps that they are catching are from nests with many developing wasps!

A meat-baited trap full of European Paper Wasps – this indicates that there are nearby nests full of wasp larvae.

At this, another friend present asked me why folks these days trapped wasps with meat – he remembered his grandmother having lots of success baiting wasps with beer. The answer is that it depends on the season, and what part of their life cycle the wasps are in…

Early on, a wasp nest is focused on growing: laying eggs and raising larvae to adulthood. Little humans need healthy food, protein to turn into muscle tissue. The same is true of young insects: adult wasps prefer to feed their larvae with protein-rich foods (any meat – caterpillars or dead deer, it makes no difference). If you’re seeing wasp nests with lots of brood cells by your home, consider putting a bit of meat, especially spoiling meat, in your wasp trap!

A nest of the invasive European Paper Wasp – note the cells capped with silk, these contain developing wasps.

Adult insects, however, aren’t going to build any more muscle than they already have. We mammals can continue to develop our musculature throughout adulthood. Insects only get bigger by molting, and almost all adult insects do not molt.

Though they don’t grow, most adult insects do spend a lot of time flying. Flying is very energetically expensive (it’s why hummingbirds are such sugar junkies). Likewise, adult wasps prefer to eat high energy, sugary foods. If you’re trying to trap wasps later in the season, when they’re reproducing less, you’ll have better success baiting them in with sugar solutions, juice, or alcohol.

Here’s good instructions for making a wasp trap – bait it however you’d like.
As always, be aware of your local wildlife when setting up insect traps! If you’ve got a bear in the vicinity, it’s probably best to hold off on trapping for a while. They’re at least as fond of meat and booze as the wasps are…

Next week: Wasp body language: how to tell if they’re aggressive.
(for real this time – none were aggressive towards me this week, so no useful photos).

Ask The Entomologist

Control of earwigs

Are earwigs our friends or foes?

That depends on the context.

Earwigs are primarily scavengers of rotting plant material. They aren’t likely to damage your garden plants themselves. As omnivores, they often help control aphids, mites, and various pest insect eggs… and I’m more than willing to put up with them if it means fewer aphids.

However, if your garden plants become damaged by other things (e.g. rot on cabbage leaves along the edges of Pierid caterpillar feeding), earwigs may contribute and make the damage worse. It’s not uncommon to find earwigs when shucking corn, often in the tassels, sometimes feeding on the corn itself. It’s rare for them to damage harder-skinned fruits such as apples (the skin tends to be too hard for them to get past on their own), but they may become a nuisance if fruit damage from birds is present.

If you want your earwigs gone, I’m willing to provide a bit of advice. Try removing their shelters near your home (big rocks alongside the house, piles of old boards, wet mulch, pretty much anything decaying, etc.).

Outside, earwigs can be trapped by burying small tin cans (pet food cans or tuna cans are the perfect size) or disposable cups level with the ground, and filling them with cheap cooking oil (leave at least an inch of space from the top). Earwigs and similar insect scavengers will try to feed and will fall to their oily deaths. Depending on your local wildlife, this may be an unwise tactic.

If they’re inside the house, set up a trap of moist newspaper rolled into tubes, containing a small amount of bait (rolled oats, wheat bran or wheat germ). The main idea is to create a dark daytime shelter that the earwigs will like. Check your trap every two or three days. When opening your earwig traps, either bag and trash the whole setup… Or shake the earwigs into an empty container to give them to chickens as feed (the flock my folks kept loved eating them).

If you want to wage more aggressive warfare against earwigs, consider using diatomaceous earth. This comes from ancient freshwater sediments rich in the sharp glass-like remains of tiny algae called diatoms. It controls insects by damaging their outer waxy layer, causing them to die from dehydration. Diatomaceous earth should be spread in areas earwigs are likely to cross, entrance points to your home and places where they are abundant. If in the garden, ring the bases of plants you are concerned for with it.

If you want to go the chemical warfare route, both permethrin and carbaryl (Sevin) have forms that are safe for use around food plants. I would recommend using a bait rather than a spray poison, as it will kill fewer of your beneficial garden insects like ground beetles and lady beetles. If earwigs are your target, you should be putting down poison in the evenings, as they are primarily nocturnal, and that way you’ll waste less of your bait on non-target insects.

Consider commenting below to let us know how your earwig control efforts are going!
What other insects would you like to hear about?

Next week: Wasps!