By BRUCE LUND
Inspired by the story about baby falcons in a valley backyard a couple of weeks ago, another Progress reader sent me a picture to identify. A former Overton resident who now lives in California, Laverne Moody, was visiting last week (to enjoy the hottest part of the year again?) and discovered and photographed a BIG insect on a house wall. Wanting to know what it was, she sent the picture to an on-line insect identification site and got a “we-have-no-idea” response. So Laverne thought phooey on them and called me to ask if she could send the picture – which she did with a note saying she was certain that I would be able to tell her what she had found. Phew, the pressure was on!
Fortunately, Laverne had gotten a good picture of an adult Antlion, clearly showing its long narrow shape, large net-veined wings, and (especially) its long antennae with curved tips.
When folks see an adult antlion, they often mistake it for a dragonfly or damselfly. However, the long antennae are an easy-to-spot characteristic that tosses the identification to an antlion. Antennae of dragonflies and damselflies are so short and small that it can be hard to see them at all.
While the adults are fairly common and (as can be seen in the picture) are fairly distinctive looking insects, most folks don’t see them because they fly about at night. Instead here is one of those few examples where instead of recognizing the winged torpedo looking adult insect, more folks are familiar with their curious larvae that look like miniature armored tanks.
Female Antlions deposit eggs in sandy soil where they soon hatch out tiny larvae. These crawl over the surface of the sand leaving winding trails which have a doodling look: this is the origin of another common name for this insect, “doodlebugs”.
When the larvae decide in their tiny brains that they have arrived at the perfect location for digging their pit, they create a circular furrow. Then, while moving backwards following the furrow, they flip their heads to toss sand up and out to one side. As each larva works toward the center, about a 2-inch deep funnel-shaped pit is created until the slope of the sides is at the steepest angle possible that the sand can retain without falling in except from the slightest disturbance. (Geologists have a wonderful phrase for this delicate balance: the Angle of Repose).
Having built its pit, the larva ceases its labors to wait patiently at the bottom with its two huge pincer jaws sticking above the sand. When a luckless ant or other crawling insect tumbles into the funnel, the antlion snaps its jaws until it impales the prey and injects paralyzing venom to liquefy and consume the catch.
This sounds like a simple and straight forward process and once an insect tumbles in, the odds are stacked in favor of the antlion larva. But nabbing the prey is a frantic business: as the prey frantically and desperately tries to climb out, the antlion wildly snaps its jaws and tosses sand up and around the sides of the pit to keep the footing loose. This makes it all but impossible for the ant or beetle or spider to crawl out and causes the critter to slide back down to the snapping jaws. All this is quite a show and many a rural youngster has amused themselves dropping insects into antlion pits to watch the action.
The number of antlons living in a few square yards of sandy soil can be amazing with scores of wall-to-wall antlion pits. It makes me wonder how there can be enough crawling insects to feed them all. It must work for them as antlions and their relatives are abundant around the world in arid lands.
As ferocious as antlions look and act, they are harmless to people (including to children with tiny fingers) and it’s not uncommon for folks to take a few scoops of antlion populated sand into jars and watch them excavate their pits and then to drop in ants or other bugs and observe them catching their prey. Eventually, the larvae grow large enough to stop feeding and form a sand-covered cocoon in which they go through a complete transformation to the adult flying form (like caterpillars change to butterflies). So, if one puts a screen over the top of a jar and lets it sit for weeks, you may get to see the adult antlion. It’s a pretty cool and easy experiment to try at home.
A NOTE TO READERS: Many of you have told me how much you enjoy my natural history articles. And at least once when my column got bumped for lack of space, the paper got an email asking what happened. So that the editor isn’t deluged with complaint letters (hah!), this is to explain to faithful readers that my columns will change from regular to occasional from now on.
Advancing years have caught up with us and while Flo and I love our Moapa home, we recognize we are at a place in our lives where we need to be proactive and simplify our lives in ways that better meet our physical and mental abilities. So we are moving from the responsibilities of caring for a house and yard to a condominium in Las Vegas. We’re also cutting back on activities and commitments which for me, includes reducing my columns from weekly to occasional.
I certainly have enjoyed writing them and I thank the many folks who have told me how much they like them.
Bruce Lund is a retired biologist and has a lifelong love of nature instilled by his grandparents and some remarkable teachers. He has lived with his wife, Flo, in Moapa since 1997.
