Welcome back, bug fans. With spring slowly suffusing back into the soggy, snow-flattened earth, and an army of winged, nectar-starved beasts in its wake, you might, rightly, be asking, “Hey, Bug Gal! where the hell have you been?!”
The answer: unofficial maternity leave. That’s right. Last summer bore witness to the arrival of our own little bug, whom we affectionately refer to as the “little ‘wig.”
The moniker owes its origins to a moment of What-Would-David Attenborough-Do inspiration that compelled us to reveal the baby’s sex by forcing our loved ones to study a photograph of an earwig’s caboose. Earwig “pincers,” you see, differ in shape depending on the insect’s sex (straight = female, curved = male).
Knowing we’d compelled curious loved ones to Google phrases like “earwig: anal forceps” while at work brought us tremendous joy (#teachablemoments).
So, in honor of our beloved (and straight-pincered) little “wig,” this month’s column will highlight two Billings-area baby bugs: the larval stages of the antlion and golden tortoise beetle.
And fair warning (on the off chance some of you are attempting to be adults today): the talk of butt stuff has only just begun.
Golden Tortoise beetle larvae
Here’s a phrase you probably thought you’d never hear: fecal umbrella. You … are … welcome. How about crap canvas? Poop parasol? Shit shield? OK, I made up the last three, but the first is legit. Fecal umbrellas are defensive structures that the larval stages of certain tortoise beetles (family Cassidinae) build.
One species, the golden tortoise beetle (Charidotella sexpunctata), is particularly common. If, like me, you spend a good bit of summer battling bindweed, then you’ve probably spied them, as the beetles are particular to plants in the morning glory family (Convolvulaceae).
Like all tortoise beetles, the adults possess low-hanging, flanged wing-covers reminiscent of a tortoise’s shell. What makes the adult beetles hard to miss, though, is their stunning metallic coloration, which the insect can quickly shift from a pure, molten gold to a rainbow-hued swirl to a dull red, depending on its “mood,” or if threatened.
An example of structural coloration (as opposed to pigmentation), it’s achieved when fluid secreted into tiny chambers in the beetle’s cuticle alters the chambers’ size and, thus, the refraction of incoming light. Sadly, these colors disappear with the beetle’s death.
The visual beauty of the adults is only enhanced, in my opinion, by the behavior of their caca-collecting young.
To defend against backyard baddies, golden tortoise beetle larvae glue old, molted “skins” and dried fecal matter (frass) to a moveable structure at the tip of their abdomen called an anal fork. The larvae usually curl this fork and its fecal fan over their backs when at rest but will flick the shield up and down in the face of incoming predators.
Research suggests the shield derives its defensive power from noxious compounds present in the beetle larvae’s poop. These compounds occur naturally in the beetle’s food plants and are sequestered for later use during larval digestion of the plant tissue. According to researchers, the fecal fan’s toxic funk is enough to deter small insect predators like ants and aphidlions when they touch the shield but does little to repel larger enemies like assassin bugs.
The mental picture this scenario conjures is too good not to indulge. Imagine: you, warning off a potential mugger with nothing more than a parasol generously smeared with your own feces.
Hey, don’t let waste go to waste, yo.
If you’ve ever seen the movie “Tremors,” (a keystone of the horror Western genre), then you’re already abstractly familiar with antlions, as they are the real, soil-dwelling beasts that inspired the creation of the film’s fearsome foes, the graboids — huge, worm-like, subterranean monsters that use surface vibrations to locate their desert prey: Kevin Bacon and friends.
Real antlions, though, are even neater.
Unlike graboids, antlions are not worms but, rather, insects from the family Myrmeleontidae in the order Neuroptera (the “nerve-winged” insects). The peculiarities of these creatures begin with the fact that the babies are way more famous than their parents, which are often mistaken for pallid, weak-flying damselflies.
Indeed, when people talk about “antlions” they’re almost always referring to the insect’s predatory larvae: fleshy, raisin-sized beasts with bristly backsides and flat, spade-like heads flanked by a pair of spiny, sickle-shaped jaws that the creatures hold open, to speed up the chomp.
The best-known antlion larvae (especially in the arid West) are the pit-diggers from the genus Myrmeleon.
Most antlion larvae, you see, simply wait at the soil’s subsurface — like jerks — for the arrival of passing prey. Myrmeleon larvae take it up a notch. These diminutive “demons of the dust” excavate cone-shaped traps in loose sand and soil by scooting rapidly backwards (the only direction they can scoot) in a series of concentric circles. At the same time, the creatures shovel sand up and out of the nascent pit with their flat heads. The result is the formation of a near-perfect pitfall trap. The beasts then bury themselves at the pit’s base, leaving only their jaws exposed (and agape — as seen in this video filmed by media artist Ian Lyman.)
The insects maintain this position until an ant or small beetle wanders heedlessly into the sandy snare. Often, gravity, grade and the slope’s slippery shifting are enough to bully the little “bug” into the larva’s monstrous maw. If not, though, the young antlion will use its shovelhead to fling sand at the escapee, forcing it, via landslide, back into the pit. Then snap go the jaws. At this point, the prey is pretty much screwed; even final, desperate struggling is usually for naught thanks to a crop of forward-pointing bristles on the antlion’s body that help anchor the predator in place.
With its victim secured, the young antlion injects an enzymatic brew that both paralyzes the prey and turns its tissues to soup, which the antlion sucks up through hollow jaws. The victim’s juiceless carcass is then pitched — like so much flotsam — from the pit, often landing near the trap’s rim. The pits of well-fed larvae will often be ringed with a posey of departed prey; a welcome wreath gone wonderfully macabre.
Interestingly, research on antlion pits suggests that while such detritus may attract more prey to the area, a trashy pit porch also slows down incoming critters, decreasing the chance prey will bumble into the traps. It helps, then, that antlion larvae tend to build their pits in close proximity to each other as the messy habits of one larva may benefit its neater neighbors.
Compared to their ferocious spawn, adult antlions seem another species entirely. The lacy-winged insects, which hatch from a sand-covered cocoon buried beneath the larval pit, are delicate, short-lived creatures.
In some species, (Glenurus gratus, e.g.) the adults boast a canvas-worthy, mottle-winged beauty; mini Pollock paintings in flight. Most, though, are rather plain; resembling washed-out, weak-flying damselflies.
Adult antlions are largely night-loving creatures that spend days camouflaged against the branches and grass blades to which they cling. Thus, they are rarely seen unless disturbed. They are also more omnivorous than their babies, eating both pollen and nectar in addition to small invertebrates.
To find Myrmeleon larvae in our area, look for their characteristic pits in sandy soil beneath overhangs or ledges on and around the Rims. If the pit is active, the little dirt devil will be just below the soil’s surface at the pit’s base. To catch one, scoop your hand under the pit, making sure to scoop a few inches below the pit’s base and lift. Examine the scooped dirt for what looks like a dusty bean. If it starts scooting backwards, you’ve got yourself an antlion, friend. And don’t fret, these beasts are harmless to humans.
To watch the creature’s pit-making in action, just place one in a deep bowl of sand. Once the pit’s constructed, throw in a couple of ants or small beetles or a Kevin Bacon mini-fig. And just remember, “That’s how they git you. They’re under the goddammed ground!”