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: insect
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.
Here’s a snow midge I found a few days ago at Hildacy Farm Preserve. I’m not positive about the species, but perhaps Diamesa nivoriunda. I only saw one, but related members of the genus are reported to swarm during the winter.
What I’d love to know is why the halteres are yellow. They seem to be yellow on majority of diptera I’ve seen, and I’ve never stumbled onto a paper discussing why that is. All I could find was the sentence “Haltere color is often used to distinguish between species” in a Drosophila book .” If you know of a paper, please send link ASAP. Am dying of curiosity.
I was out looking for the elusive snow fly yesterday but found this, instead: an eastern stonefly (Allocapnia recta), a member of the Capniidae (small winter stoneflies). At least that’s what I think it is. Larvae are active during the winter, and adults can fly and mate even when temperature is in the teens. Pretty incredible to see them flitting around on a cold day when other insects cannot even move. At Hildacy Farm in Media, PA. Probably emerged from the nearby Crum Creek.
Apple oak gall (Amphibolips confluenta or Amphibolips quercusinanis), backlit to show leaf-like venation. Second photograph is a cross section showing where the wasp larva develops. I’d love to know what the spotting does, if anything.
Cynipid wasps love oaks for some reason — over 3/4 of the 1300 species use Quercus as host. People argue about why that’s the case (e.g., Ronquist et al. 2015). Even Alfred Kinsey the sexologist weighed in, back in the days when he was obsessed with gall wasps.