Here are four anterior close-ups Pyractomena borealis. The telescoping head allows the larva to inject (via curved, hollow mandibles) a numbing agent into snails that have retreated inside their shells. The antennae and maxillae are also partially retractable. When a larva is done feeding on a snail (or slug or earthworm) it will de-slime all of these parts with the hooked, fingerlike projections of the holdfast organ (pygopod) located on the last abdominal segment. The head is also fully retractible (see previous post). These larvae are extremely active, so really hard to photograph.
Tag Archives: coleoptera
Pyractomena borealis (Lampyridae) exploring the surface of trees on a warm winter day in February. The third photograph shows how they can retract their head under the carapace like a turtle. At first I thought they might be foraging — they are highly predaceous, and hunt slugs and earthworms (in packs!) by first injecting them with paralytics. But they might have just been looking for a place to pupate, because it’s time for that. Adults will emerge sometime in early Spring to be the first fireflies in the area. The larvae are bioluminescent, too. The hypothesis about why the larvae glow is that it evolved first as an aposematic trait in larvae, warning mice and toads of the presence of lucibufagins, steroidal toxins in the hemolymph. It’s thought that the adult habit of using flashes is secondarily evolved, millions of years after the larvae evolved the ability to glow. The ability of larvae to glow even predates the origin of the Lampyridae, I gather. For more enlightening details, see Branham and Wezel (2003), Stanger-Hall et al. (2007), and Martin et al. 2017.
Found a bunch of these flat-faced longhorn beetles on a dying tree a few weeks ago. I’m fairly confident it’s Astylopsis macula. But there are a gazillion genera of Lamiinae, so I’m happy to be corrected. Would also be very happy to hear from anyone who knows what elytral pits do, other than providing handy identification. I’ve wondered about that for years. Are they vestigial patterns from forewing ancestry? Sound-dampening trick to elude echolocating bats? Are pits just decorations, useful in crypsis or for intraspecific recognition? If you know, would love to hear from you.
Mating pairs of red milkweed beetles (Tetraopes tetrophthalmus) are not rare (they can couple for hours at a time), but I thought this couple looked cute, in a worried sort of way. The half-lidded expression is because their compound eyes are bisected by their antennae. Beautiful beetles.