Ask The Entomologist

Our inchworms and their violent kin

Mike found this inchworm in the woods recently.

Inchworms are moth caterpillars, specifically members of family Geometridae. Their family name means something like “the earth measurers”, after how they fold up and then stretch themselves out, like a surveyor’s measuring rope.

As you can see, this little fellow nearly lives up to the name.
About 6 millimeters too short, though.
And its classic gait. – note that it has all three pairs of real legs right by its head, at the left. The footlike things on the right are just extensions of the abdomen.

Ours around here aren’t all that interesting. They’re pretty standard caterpillars – standard herbivores, or opportunistic omnivores. And, like most larvae, they are very hard to identify beyond family until they molt to adulthood.

Hawaii, however, has an interesting lineage of carnivorous inchworm caterpillars. The prevailing thought is that when the Hawaiian islands were first colonized by insects, few of those pioneering species were predatory. After all, carnivores require a healthy prey population to do well. As time went on, a certain group of inchworm caterpillars adopted a predatory role – after all, there wasn’t much competition.

A good videoclip of an ambush hunter inchworm.

As time went on, the caterpillars radiated into different species with different preferred prey and hunting tactics. Some mimic twigs, others mimic leaves. Some rely on ambushes alone, while others bind up their prey with silk before consuming them. The ones I first read about prefer hunting flies, while others eat things as strange as snails.

Looking at a caterpillar move, it’s initially hard to fathom it ever moving with sufficient speed and dexterity to grab a fly, but amazing things can happen with time and the right selective pressures.

And another brief video of one of the fly-hunting species.

While we in the lower 48 do have a few omnivorous caterpillars, I’m not aware of any strict carnivores. Omnivory is easy to understand – say you have a passel of siblings all competing for the same leaves… sooner or later that sibling rivalry will result in somebody taking a bite out of a brother, and realizing that he’s pretty decent food.

Many insect mothers lay extra unfertilized eggs, just in case some of the early hatchers are in the mood to eat potential siblings. Gives the slow larvae a bit longer to escape their hungry siblings.

Wildlife

Bears know that the apples are ready…

It’s time to pick apples – at least according to the local wildlife. This weekend, we happened upon an adult black bear and her cubs munching on the apples down by the Trego railroad crossing in the wee morning hours.

Bears aren’t too picky about ripeness. Like many mammals, they’re attracted to the smell of fermentation – (the smell indicates a fruit has the highest calorie content it’s going to get). As apples get ripe (and then overripe) they become even better bear attractants.

Can bears become inebriated? Certainly! Glacier Park had a number of incidents back in the 80’s. Several railroad spills released thousands of tons of barley and corn. Buried by cleanup efforts, much of the grain fermented anaerobically, producing high volumes of alcohol. Upon emerging in the spring, bears promptly dug up the fermented mash, wish predictable consequences.

While unattended grain can ferment well, fruit left to its own devices rarely produces enough alcohol to have an effect on large mammals. Bears may be in your apple trees in the near future, but at least you won’t have to worry about them being drunk and disorderly. Not from that, anyway.

Community

On the sex lives of bandwing grasshoppers

I know that our grasshopper levels are higher than desirable at present, but today I caught one of my favorite types. A bandwing grasshopper, as opposed to their slantface and spurthroat kin (our most economically damaging grasshoppers here tend to be spurthroats).

While beetles aren’t always the most discriminate of lovers… grasshoppers tend to be rather selective in their choice of partners.

Bandwing grasshoppers have showy courtship displays – males fly, preferably into a breeze, staying fairly stationary but bobbing up and down. As they do this, they make clacking noises with their wings (entomologists call them “crepitations“), and show off their bright wing colors. Here’s a great example video of this behavior.

Females come to admire the display and assess the performing male’s suitability as a sperm donor. Males, also attracted by the display, come and join in. After all, if other males are performing here, there must be some females nearby who might be interested in me!

If the performing male(s) are sufficiently impressive, and have the right wing color, and the right clacking sound, an interested female will respond in kind. She’ll fly up, clacking her wings, before landing near a suitable spot for romance.

On the ground she’ll make further investigation of her suitors – someone who looked appealing in the air might not on the ground. If not interested, she’ll hop away, and may raise her hind feet and brandish them threateningly at the suitor.

If, however, her meets her standards, there are a variety of come-hither beckons, which vary from species to species. Common variants include moving the hind legs up or down, to provide better access to the abdomen. There may also be chirping noises, leg-stamping dances, and stroking with antennae.

Mating time varies from less than half an hour to upwards of half a day, depending on the species.

While I know that my fondness for grasshoppers is thought a bit odd, the Judeo-Christian god had a soft spot for them as well. When I see grasshoppers arcing over the fields like breaking waves, I hear the words of Joel in my head, and think of how terrifying the lord’s army of grasshoppers can be. “Σαλπισατε σάλπιγγι ἐν Σιών!”

Weird Words

Weird words: Petrichor, stone’s blood.

Stepping outside after this weekend’s much-needed downpours, I was met with a familiar fragrance. The smell of the earth after rain, sometimes called “Petrichor”.

This is a fairly modern word, cobbled together by a couple of scientists in 1965.
It’s derived from two Greek word roots. Petra (πετρα) meaning “rock” and ichor (ιχωρ) meaning “blood”. But ichor is usually a special sort of blood – the juice that flows in the veins of a god or giant, perhaps a monster, not a mere mortal.

Petrichor’s scent is strongest after rain beats down on hot, dry soil. When rain pummels the earth, it stirs up waste from tiny soil bacteria called Actinomycetes… tossing tiny particles of something chemists have named “geosmin” into the air.

Interestingly enough, this same compound that brings us that lovely post-rainstorm aroma is also responsible for strong earthy flavors.

It’s why catfish and other bottom-feeders can taste a bit muddy at times (especially when caught in hot weather). It’s also why fungi and vegetables can taste a bit earthy, even after being thoroughly washed. Personally, I’m fond of strong-flavored catfish and earthy beets and mushrooms, but to each their own.

If you’re not fond of those earthy flavors, consider adding an acid during cooking (such as vinegar). This will cause geosmin to break down and give you less-fishy tasting fish or vegetables that taste less of dirt.

On a more entomological note, mosquitoes are attracted to geosmin’s smell in preparation for laying their eggs. A number of entomologists and chemists are currently experimenting on traps using geosmin extracted from beetroot skins.

I look forward to seeing how geosmin trap technology develops – but I suspect it’d be quite possible to come up with a homemade trap based on the same principles that’d work well. After all, if we can collect and destroy many mosquito eggs, we should see some dint in next years’ mosquito populations.

There are few scents I’d rather breathe in.

Ask The Entomologist

Amorous Beetles

With fire so near to us, and this oppressive ground-clinging smoke left after last night’s badly-needed rain, I’m reminded of beetles. Specifically, amorous beetles.

Wood-boring beetles, such as jewel beetles and long-horned beetles, are attracted by the smell of distressed trees. Burnt forests draw them in, as does the smell of wood on the air after I’ve been running the stump grinder.

But, much like humans, male jewel beetles are visual creatures. What really gets them in the mood for love is the sight of a female. Or something that looks a lot like a female.

The Emerald Ash Beetle is an invasive jewel beetle, currently approaching us from the East. It’s just a matter of time until it gets here, and entomologists are working hard at devising good traps for it. Traps are most effective when they match the beetles’ taste in mates’ colors – light green (preferred by the males) and purple (preferred by the females)…

Many insect traps also use sex pheromones to complete the illusion of “single bugs near you looking for love”. But either way, the fragrance of a distressed tree is a near-must if you want to attract its wood-boring insects.


In most cases, that is. Distressed plant scents aren’t always involved.

Julodimorpha bakewelli male having a good time with the most attractive female he’s ever met.
(photo credit: Darryl Gwynne – one of the two young entomologists who discovered this phenomenon)

Australia very nearly lost a large and very attractive species of giant jewel beetle, Julodimorpha bakewelli, thanks to male sexual confusion.

You see, just as in the Emerald Ash Borer, color and sheen are very important to the Australian Jewel Beetle. Females of this species are a lovely golden brown, with wingcases covered with little dimples that catch the light. To males of this species, the ideal female is one much larger than them – well-fed, healthy, and able to lay many eggs.

Unfortunately, textured beer bottles discarded along Australian highways proved irresistible to the male beetles. “Her size! Her color! The way she glimmers in the light!I’ve never known anyone this stunning”

It was simply impossible for females to compete for their males’ affections. All across Australia, female jewel beetles were spending nights alone by themselves in the Eucalyptus trees.

Meanwhile generations of males spent themselves on discarded beer bottles who never reciprocated their affections. The most beautiful female jewel beetle or a beer bottle? Males had a clear preference.

As the years went by, it became clear that the giant jewel beetle birth rate was severely affected. Surprisingly, the beer industry stepped in and designed a new bottle, less attractive to beetles. Thus saving the Australian Jewel Beetle from extinction. Here’s a brief video on the beer-bottle-loving beetles.

We can only dream of stumbling on something as attractive to control our lumber pests.

Community

Backwoods Accordion Festival was well attended

Trego’s Backwoods Accordion Festival was well attended Saturday. Music began at the Trego Pub at three and continued until 9 pm, featuring: Ray Jacobs and Friends, Accordion Demolition Demo, Ol’ Santi, Shirley Jacobs, Euphonium Spaceship, and Shrimp Louise and the Fiddler Crabs.

Despite the heat and gathering haze, folks gathered from near and far – the Flathead was well-represented, though Lincoln County residents made up the majority.

Throughout the festival, attendees broke into spontaneous dance – waltzes and two-steps, among others. Thanks to the venue, attendees both ate and drank well. Thanks to the multitude of talented musicians, many of us walked away with new songs in our heads, spring in our steps, and appreciation for our community.

We look forward to next year’s festival, and the many musical events between now and then.

Ask The Entomologist

Cicadas – not just Brood X!

Chances are you’ve seen internet articles about the mass cicada emergences that’ll be happening across the eastern United States this year. Here’s a decent writeup from the National Park Service.

Periodical cicadas are named for the long stretches of time between their emergences (13 or 17 years, depending on the lineage). The thought is that this makes them an unreliable source of food for predators – it’s hard to be a specialist wasp if your food species vanishes and is unaccessible below ground for over a decade at a time.

And, when you emerge, surrounded by thousands of others like you, it’s statistically unlikely that you’ll be the one who gets eaten – be it by bird, dog, or unattended small child. Though many of your kin will be devoured, you’ll probably be safe. It’s the same tactic the now-extinct Passenger Pigeon used. Passenger Pigeons built undefended nests on the ground, and relied on numbers to make any individuals odds of survival better. A tactic that worked excellently until it didn’t.

Here we have a little member of genus Okanagana, the whip cicadas.
Fittingly for this area, they’re named after one of Canada’s First Nations which spoke a Salish tongue.

While we don’t have periodical cicadas (genus Magicicada) this far west, we do have other types of cicadas, especially genus Okanagana. I’ve been hearing their males sing in the trees on my drive back from work over the past couple of weeks. One way cicadas avoid predators is by being active in the sweltering heat when nothing wants to hunt. Cicadas cope with the heat by drinking tree sap nearly constantly, and releasing excess moisture through pores in their thoraxes, much like how we humans sweat to cool down.

Our cicadas here have life cycles maxing out in the 3-year range. As such, these species can be pretty reliable hosts for certain predators, like the cicada killer wasp… but our cicadas lead a charmed life. The Western Cicada Killer Wasp only goes as far east as Idaho, and the Eastern Cicada Killer Wasp only really goes as far west as the Dakotas.

Our local cicadas are convinced that this truly is God’s country.

An Okanagana cicada I met last fall – note that this one has brighter orange markings.
Wildlife

My first days in Trego

This past week held the anniversary of my moving up to Trego to join my wife, Sam… As such, it also held the anniversary of my meeting the best firearm evangelists I’ve yet encountered.

The bears.

The two delinquent bruins, about a month before I moved up to Trego.
Note the radio collar on the left bear – both have them.

A year ago, I wrapped up my Masters Degree project, describing several new species of Kentucky cave beetles, and began the long drive out to Trego, MT. I believe it was the evening of my second day here in Montana that they introduced themselves…

Just as Sam and I were settling in for the evening, we received a panicked phone call from her mother. She was sufficiently agitated for me to hear her some distance from the phone… As it turned out, Sam’s father, Mike, had stepped out onto the porch to shout at couple of gangly young grizzlies, encourage them to get a bit further from his house. But he had a little overweight Pomeranian who had other ideas – she sprinted out the door past him, intent on getting between him and the bears. Despite the size disparity, she startled those bears and made them run… And, as they were running, she pursued them, a good 300-some feet.

Mike couldn’t let her be alone out there with them, so he ducked back inside, grabbed some slippers & the nearest firearm, and headed out after his wee beastie. It’s at this point in time that Sam’s mother called. Sam hurriedly grabbed the keys and produced a couple of guns. She passed me one which I straightaway handed back to her.

At this point in my life, I’d never fired a gun before, and I’m somebody who believes in doing things well. I thought I’d have better combat utility with a walking stick, and took a promising one.

So, off the two of us flew, leaving our own irate wee beastie behind us. Sam at the wheel, bouncing the truck down the old road to her folks. As we arrived the two young delinquent grizzlies were reconsidering their flight from a certain overweight Pomeranian… but they backed off as we raced up in the truck.

Sam passed me her gun, and bailed out to catch the overweight Pomeranian (who refused to get behind Sam’s father), and we retreated back to her folks’ house. While Mike’s seven rounds of 22 weren’t great comfort with two bears at close range… it was a sight better than my walking stick.

The next day we could see the bears from our house, as they enjoyed a neighbor’s water feature. It took about a week for Fish & Game to trap them, and all the while I was waking up to nightmares of bear home invasion. As soon as they were captured and removed from the area, I began learning to shoot. One could scarce ask for better motivation, and I practiced devoutly.

Shortly after our first sighting of grizzlies this year, I had another dream about them staging a home invasion. This time, I was armed, and the dream ended much better for us. While I’d hate to have to shoot one, it’s nice to be capable of doing so, if need be.

Wildlife

Neighbors with similar interests.

Yesterday as I was working at tearing apart some dilapidated buildings for building material, I came across an unexpected find. A bat – genus Myotis, I think. Sheltered in one of the grooves of the roofing tin.

It’s always nice to find other folks who appreciate insects as much as I do. There’s enough insects to go around – I’ll not worry about this fellow’s competition. The bat seemed to be in good health, with no sign of White Nose Syndrome, a fungal disease which has decimated North American bats.

White Nose Fungus is native to Europe, but was introduced to eastern North America about 15 years ago, and bat die-offs followed. At first folks thought that a certain European caver’s unwashed gear could be to blame, but now it’s thought that European bats might have spread the plague themselves, after immigrating to this country as stowaways on container ships.

Fortunately, native bats finally seem to be developing resistance to the disease… or rather, most of the susceptible bats have died, and the ones remaining tend to be of resistant stock.

Along with the bat were an abundance of leaf-footed bugs and paper wasps which attempted to overwinter with the roof as shelter. While some insects may have overwintered here successfully, the only ones remaining are those who didn’t quite manage.

The bat skittered away from the camera, and seemed to be trying to hiss at me, though I couldn’t quite hear the vocalizations. Then it winged away to take shelter in a nearby Douglas Fir, shortly before hail encouraged me to wrap up my roof demolition.

I’ll hope to see them again later this summer, diving for mosquitoes and mayflies in the gathering dusk.

Community

A litter of Cat-Faced Spiderlings! (Kittens?)

If you recall last fall’s beautiful cat-faced spider, you may be pleased to learn that her eggsac survived the winter, and hundreds of her orphans are now dispersing out along our windowscreen and wall.

Sometimes it is hard to pick out the separation between cephalothorax and abdomen, especially when spiderlings (“slings”, for short) are clumped together. They quickly spread out when somebody looms close, as I did with my camera. When the spiderlings are moving, it’s easy to see that they’re built like adult spiders, with a pinch dividing their two body segments.

Here the spiderlings are, clumped together, viewed from inside the house.
As I moved in with my camera, they rapidly dispersed – a sensible way to avoid being eaten.

I love doing infant photography.

Here are more slings, arrayed on their strands of webbing, outside of the eggsac their mother was guarding last autumn.
The evening sun silhouettes moving spiderlings, making it easy to see their body regions, or “tagma”.