Firebug (aggregation) - Pyrrhocoris apterus
I've noticed a good handful of large-sized insect aggregations over the last few weeks, and these pictures are an example of one of them. My favorite of the year actually. Many similar showcases have been seen on this blog before, but there's one little thing different about this collection of red individuals. As these Red Bugs gather on the sunny side of this tree to absorb the sun's warmth and drive their metabolism, I couldn't help but notice an individual different from the others. Specifically, the individual seen in pictures 2, 5 and 9. This is a freshly molted adult (technically termed as a "pharate") Firebug! It appears more fire-inspired than the adults, although it lacks the deep crimson along its body. That will appear after exposure to sunlight and the air gradually dries and darkens this specie's outer cuticle after molting. This will eventually result in the dark-colored face, crimson body, and black patterning appearing on the abdomen and the reduced wings (in the form of spots). Looking at the freshly molted Bug, it's hard to believe that such distinctive colors and patterns will manifest with the full sclerization of the adult exoskeleton, but time is a powerful thing in the insect world.
On the subject of exoskeletons, if you look carefully in Picture 1, you will find the shed exuvia of a Firebug next to the aggregation. While I didn't observe longer than a few minutes, it's very likely that were many more shedding events over the next few days given the number of pre-adult nymphs scampering alongside the adults. If they are to molt, it would be in their best interest to remain on the sunny side of the tree to help speed up the tanning process. The sooner they arrive at adulthood, the sooner they can release more pheromones in order to increase the aggregation's size and form mating pairs before the end of autumn. Since they're so exposed, hopefully their bright colors are enough to discourage hungry insectivores from trying a sample (especially since Firebugs aren't poisonous despite their bright colors). As mentioned in many prior posts, however, strength in numbers is their greatest defense, which is all the more reason to draw more Bugs into the aggregation as quickly as they detect and sprint!
Pictures were taken on September 12, 2024 with a Google Pixel 4. And of course, there are many other insect species that form aggregations for socialization, mating and protection. Some of them may appear similar to the Common Firebug.












