Ask The Entomologist, Community

Ask The Entomologist: Fluffy caterpillars

Last week I received an “Ask The Entomologist” identification request.
What is this fluffy caterpillar? It was found feeding on blackberry bush leaves.

First off, adorable. This is a Tussock Moth caterpillar, so called after the little clumps of hair on their backs. Many fluffy caterpillars are in this group, family Lymantriidae. This particular species is called the Spotted Tussock Moth, and is native to our region. It’s not a picky eater, and will gladly eat willow, birch, and a range of other deciduous trees. We have another related species in the area, the Douglas Fir Tussock Moth, which can become an awful lumber pest, and has been linked with some health conditions in forestry workers.

Beware! While Tussock Moths’ long hairs can feel soft if you stroke them gently, they often conceal shorter special defensive hairs! These “urticating” (itchy) hairs are like tiny spears and can be quite painful – some even come with venom. Many types of Tussock Moth urticating hairs can cause allergic reactions, the Spotted Tussock Moth (the one above) has even caused one case of anaphylactic shock. Even if you’re not allergic to the caterpillars, there’s the possibility of bacterial infection if the hairs break off beneath your skin.

Tussock moth caterpillars can prove even more dangerous if eaten! Whether by livestock (abortions in mares, presumably others as well), pets (tongue rot documented in dogs), or unattended toddlers (often surgery, no deaths reported yet…) . The most serious condition resulting is that the eaten caterpillars’ hairs can puncture the digestive tract. This may cause bacteria to seep from the intestines into the body cavity, and can cause serious illness. While a healthy organism may be able to survive this, it often proves fatal to unborn young, which don’t have sufficiently developed immune systems.

These caterpillars can be perfectly safe, and kids can have a great time watching them grow up into pretty little moths, but do be careful! If you think you, your kids, or your pets have been injured by contact with a caterpillar, Mayo Clinic has some medical advice. If you want to kill your Tussock Moth caterpillars, I suggest rubber gloves and a jar of soapy water.

Looking forward to more bug questions,


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

Wasps… they’re not always out to get us.

What says midsummer better than unexpected wasp nests? Buzzing uncomfortably overhead, nests full to bursting with developing young. Dreadful things, right?

What would you say if I told you that aggressive wasps (think of your stereotypical Bald Faced Hornets) aren’t the only kind out there? Even within a single species, there are a wide variety of levels of aggression.

If a wasp is going to be aggressive to protect her nest, full of her offspring and her sisters’ offspring, she really has to go all out. If a wasp doesn’t give her all when driving potential threats away, chances are that the nest will have to repel more attacks, and the nest will be more likely to be detected by more dangerous predators! Predators who will attack and destroy that nest, despite angry wasps and stings. Both mammalian predators (bears, humans, etc.) and insect predators (especially ants!) are more likely to attack nests that reveal themselves by being aggressive.

While bears are stereotyped as being very fond of bees’ honey, they also relish eating the “brood”. “Brood” are the developing larvae or pupae that will grow up to become wasps or bees. While you can only get honey from some sorts of bees… you can get delicious brood from any active bee or wasp nest!
Think of snacking on sugary fresh fruit… now think of eating a ham sandwich… Which one makes you feel more full? Bears, especially young ones, love protein-rich young insects.

There’s another strategy for survival. What if the wasp was sneaky, stealthy, and conflict-avoidant instead of being crazy aggressive? It turns out that this is a valid strategy for survival, too. Think about it – if nobody knows the wasps are there, nobody will be trying to eat their brood!

Different colonies of the same species of wasps often vary widely in how aggressive they are! Not all paper wasp nests are terrible… I’ve certainly met some aggressive ones when cleaning roof gutters and peeling off siding, but I’ve met others of the same species who wanted nothing more than to escape notice! Look at this nest, tucked below the hinge of our vehicle’s front passenger door:

These wasps had no interest in attacking us – I got within 3 inches of them with my camera, and none made threat displays. I only noticed them because I saw the same species of wasp flying outside of the vehicle as we started it up… I saw these wasps several times in a row, despite it being parked at different places… including some where this particular paper wasp isn’t common. The wasps were being sneaky – they’d found a warm place to rear their young, inside a protected shell that ants and bears alike would be unlikely to spot them in. And it worked out well for them… until I saw them and decided that I didn’t want them meeting the dog.

Next week: How to read a wasp’s body language. Apologies, folks, wasp control instead.

Ask The Entomologist, Plants

Knapweed, my current enemy.

At this time of year, many hill-slopes have turned a sharp pink-purple color. Whether you’re in Glacier or driving along 93, you’ll see its flowers in the cuts alongside the road. Here in Trego proper, you can often find it in ditches, or there’s an abundant field of it downslope from the Trego Pub. Knapweed. It’s everywhere, and looking far healthier than anyone would like it to.

Spotted Knapweed: note the black markings on the green, just below the flower blossom – these are the “spots”.

Knapweed (Centaurea sp.) is a genus of invasive plant that plagues rangeland across western North America. Its seeds made landfall on the west coast, back in the early 1900s, possibly due to contaminated alfalfa seed. Now, over a century later, knapweeds flourish across America, from sea to shining sea, more successful than they were in their homeland of southern Russia.

Thanks to the absence of the specialist insect herbivores that didn’t journey with it to the New World, and its bad taste, few things eat knapweed. And even if you are able to get something to eat it, with taproots reaching up to four feet deep, Spotted Knapweed is able to resprout with ease. Most knapweeds are only palatable to cattle early in their growing phase, quickly outcompeting grasses in overgrazed areas. To emphasize how terrible it can be in rangeland, feeding on Russian Knapweed may even prove fatal to horses.

Several common native North American grasshoppers, notably the Red-Legged Grasshopper, feed on knapweed, but they weren’t effective at controlling it. Biocontrol began in the 1980s, with introduction of knapweed-specialist weevils, flies, and wasps. Over the past 40 years they’ve proven quite useful – if there are enough seed-head feeding insects, many fewer knapweed seeds are produced each year. It’s still not a quick fix – knapweed seeds can lay dormant in the soil for at least seven years.

The Knapweed Peacock Fly: introduced for biocontrol, its maggots destroy knapweed seedheads.

These introduced bugs have done wonderful things. Knapweed is much less a problem than it once was, but biocontrol alone isn’t enough. If you happen to have knapweed on your property, the best thing you can do is to start spraying herbicide. I’ve been having decent success eliminating it with Milestone (Aminopyralid).

As best I can tell, knapweed’s one virtue seems to be a high rate of nectar production – some folks enjoy making knapweed honey.

What are your thoughts on knapweed? Have you ever tried knap honey?

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!

Ask The Entomologist

Earwigs. They’re everywhere, no?

Just yesterday morning I found one curled up inside the handle of my razor.

It’s been a good year for earwigs here, a rather moist spring. If you’ve got dead wood near your house or any other nice pile of decaying plants (even mulch), you’ve likely noticed them yourself.

Perhaps you’ve heard that earwigs crawl into sleeping people’s ears to feed… people have been telling that story for quite a while! The name “earwig” comes from Old English: either from “ēarewicga” which means something like “ear wriggler” or “ēarewic” meaning “ear dweller”. I’m glad to report that earwigs don’t *actually* feed when they do this… but they are known to crawl into ears from time to time.

All insects are crustacean refugees, you see. The first insect ancestors abandoned the rest of their crustacean kin to flee the water and its predators long, long ago. Though insects have lived on land for a long time now, moisture is still important for their survival. Insects have a protective wax layer that prevents water loss, but if this gets damaged it’s easy for them to dry out. Therefore, many insects prefer to be in a moist environment. Our ears can qualify, in the absence of better housing prospects. Today, straw mattresses being much less common than they once were, it’s unlikely that your ears will gain new tenants. Perhaps if you go camping and skip the tent…

Now that we’re in the full heat and dryness of summer, earwigs may seek shelter inside our homes, often in damp, dark places. (Think of that pile of dirty laundry in your kids’ room, the wet spot under the sink, damaged potatoes in the pantry, etc). While they don’t hurt much that wasn’t already damaged, they may begin to harm roots on well-watered houseplants.

Personally, I think that earwigs are beautiful. And remarkable – mother earwigs take good care of their offspring, something rather rare in non-social insects. They rotate the eggs, gently cleaning them of fungus, retrieve food for their young once they’ve hatched, and eventually lead the kids out of their burrow on foraging expeditions. Young earwigs play nicely with each other as well – the kids help feed each other when mom’s out.

I’ve got a soft spot for good parents, human and insect alike.

Next week – earwig pest control advice.

What’s the strangest place you’ve seen an earwig?