BugBytes: The snakefly, an insect worth bragging about

Larva

Danielle McCracken

It is believed that all modern snakeflies require a period of cold temperature (around 0 degrees Celcius) to trigger pupation, which usually begins in the spring. The above illustration is local artist Danielle McCracken’s interpretation of a Raphidiid snakefly larva in its short-lived prepupal stage, during which time the insect stops feeding and prepares to molt.

Montana’s slow burn into summer has begun. And for those of us with a consuming fondness for the mini, the many-legged, the winged and wisp-like, it’s a welcome time, as the warm, lingering days compel troops of tiny creatures to materialize, as if magicked from the pores of the earth, to exploit the season’s riches for genetic ends.

Welcome to BugBytes, a new seasonal column that seeks to highlight and explore the beauty, behavior and diversity of south-central Montana’s arthropod community, with a particular focus on insects and arachnids. Each month, BugBytes will profile a different arthropod found in our area and attempt to detail and magnify, for the reader, its fascinating natural history and economic or ecological relevance.

The goal is to revive the reader’s child within, the one that lunged at grasshoppers, reared butterflies in old-shoe boxes and marveled at the sidewalk cities and paper mansions of the neighborhood Hymenopterans.

To that end, BugBytes encourages readers to get out there, to explore what David Attenborough calls the “life in the undergrowth” and to send in pictures of what they find there along with questions and observations, which we will do our best to answer and explain with the help of area experts.

Remember, when it comes to insects and their kin, the truth can be stranger than fiction and the best fictions often find their footing in these creatures’ strange truths. So, here we go:

The Snakefly

Of Montana’s many insects, the one I tend to brag about most to out-of-staters is the snakefly, a long-necked, glassy-winged predator found only in the Western United States. With the head of a beetle, body of a wasp, and—if female—a fiendish-looking “tail,” snakeflies seem to be assembled from spare parts, like the late-night opus of some mad and meddling Dr. Frankenstein.

Indeed, when I first spotted an adult female on a flower a few years ago, I flipped out and excitedly reported the find to my ever-patient husband. He received the news with the sweetly feigned interest of someone resigned to his post as spouse to the invertebrate-obsessed. This is a role that involves frequent spider rescues, beachless vacations to jungle-bound “insect hotels” and strange wife-utterings such as, “Damn, I forgot my collecting jar. I’ll just put this beetle in my pocket. Don’t let me forget it’s in there.”

Female

Marian Lyman Kirst

This female snakefly, in the genus Agulla, was found in Carbon County.

Anyway, that original snakefly sighting compelled me to dig a little deeper into the details of this enigmatic group, beginning with the insect’s common name. As it turns out, origins of the tag “snakefly” are a little unclear. Some sources link the moniker to the adult’s slender shape and the serpent-like manner in which the insects strike at prey.

Others, however, associate the title with the sinuous movements of snakefly larvae, which are flattened, grub-like predators posteriorly tipped with a “sticky” organ that allows for marvelous, multi-directional movement, including impressive bouts of backward scuttling and even the occasional vertical clamber.

Snakeflies are also relatively primitive, dating back more than 140 million years, to the Mezosoic, when the insects first branched away from their closest living relatives, the dobson, alder and fish flies. What’s more, fossilized and amber-frozen specimens reveal that modern snakeflies look, well, strikingly similar to their prehistoric forbears.

What has changed, though, is the group’s diversity and distribution, which was greatly constrained thanks, it’s believed, to a Cretaceous-period asteroid impact. That event probably wiped out much of that era’s rich and varied snakefly fauna and, in particular, all of the tropically attuned species, leaving only cold-adapted lines to endure.

Today, there are fewer than 250 known species of snakefly comprising just two families: The Innocelliidae and the Raphidiidae, both of which are restricted to the Northern Hemisphere. Snakeflies are a wee band indeed. But what they lack in diversity, they make up for in oddity.

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Take, for example, snakefly sex, which is both family specific and, ahem, rather inventive. Inocelliid snakeflies copulate in the “tandem position.” This involves the male crawling under the female and attaching his head to her “belly.” Meanwhile, amorous snakeflies in the Raphidiidae family (to which all Montana’s snakeflies belong) assume the “wrecking” or “dragging position.” In this sexual choreography, the male hangs head first from the female while she carries him around. Is it just me or does that sound exhausting?

If things go well, though, the females will produce hundreds of eggs for eventual insertion into wood or bark crevices. She does this using her sword-like ovipositor, a lengthy rear-end katana wielded for reproductive purposes only—snakeflies, it should be noted, are harmless to humans and neither bit nor sting.

The insects are, however, voracious predators, both in their larval and adult stages. The larvae, which live either under bark or in the loose soil around shrubs and trees, hunt all manner of small, soft-bodied arthropods. The adults are likewise varied in their choice of prey—and have even been known to nosh on pollen—but they are thought to prefer aphids.

In the lab, it took an adult female Adulla adnixa just nine minutes to consume the entire aphid colony with which it was confined. Females are also often observed “wagging” their ovipositors back and forth while eating, as if expressing satisfaction with the meal.

Perhaps it’s this, the snakefly’s apparent fondness for food, to which I most relate. Or, maybe, it’s their Creature Feature-worthy mien, or nearly immutable, millennia-weathering morphology.

Whatever the reason, I’m hopelessly charmed by these insect oddballs and encourage readers to seek them out when exploring south-central Montana this summer. I tend to see them on brushes of sage stalking the scented velvet boughs, in search, perhaps, of grub good enough to wag their butts about.

Marian Lyman KirstM.L. Kirst is a Billings-based, bug-obsessed freelance writer and photographer with a background in environmental studies and science journalism, and she is currently working on a degree in entomology. Her work tends to focus on natural history and wildlife conservation. But her prime directive is to blend art, science and writing in a way that inspires others to celebrate the beauty, ingenuity, and diversity of insects, spiders and their kin.