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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.

Firebug (aggregation) - Pyrrhocoris apterus

In previous posts featuring this insect, the aggregations I've found were near the of a tree (and some of the surrounding plants) or nearby in the surrounding grasses. These Red Bugs had gathered to absorb the setting sun's heat and to search for seeds (their primary form of nutrition) and while aggregated they enjoy safety and comfort in numbers. All this is nothing new, but where urban environments and nature come together, the Common Firebug may be found in strange places. In today's post, the aggregations found here were either on or near a wooden utility pole! A while back, I noticed a similar event with a similar looking insect: the Eastern Boxelder Bug. Both insects had mistaken a piece of human construction for a tree. Looking at it from an insect's perspective, a large wooden object may very well be mistaken for tree, especially if it has similar scent cues still attached to it. A utility pole unfortunately cannot be used as a food source, but does have potential to act as a shelter from the elements or a sunning location. For the former use (as can be seen from Pictures 5 and 8), as many individuals as possible can cram into the cracks and hide away, similar to the recesses and holes of trees (similar behavior also occurs when they find their way inside a house).

Firebugs would have to rely on other creatures to expend the crevices in order to fit every Bug in the aggregation, but alas, nature is survival of the fittest. What may benefit the Firebugs more is a eusocial/colony structure whereby the younger nymphs hide away in the woody voids while the adults monitor and search for food. While not eusocial in any way, there are small inklings of such a system in the aggregations. If you look closely, your attention may be drawn more to the spotted, larger and redder adults and not the smaller nymphs that try and hide beneath them. Meanwhile, loose aggregations and single Firebugs scamper about on stone and concrete looking for a source of food and shelter. What can start as one individual in an area can quickly turn into many individuals gathering in an area thanks to potent pheromones. However, different pheromones from this insect can also cause aggregations to separate and scatter. This may be useful as a defense, but likely has more value in use for after mating (for egg dispersal) or if an aggregation grows too large and food sources are in short supply. With reduced wings to prevent flying away (in most cases) personal stuff is all the more important, and it's furthermore great that this specie can run very quickly should an aggregation need to suddenly form or disperse.

Pictures of individuals or loose aggregations were taken on June 16 and August 5, 2022 with a Google Pixel 4. Pictures of the large aggregations were taken on October 1, 2022 with a Google Pixel 4.

Firebug (aggregation) - Pyrrhocoris apterus (Part 2)

After nearly a year of waiting since the last post, we have a Firebug aggregation on display. While there are pictures from this year and last year too (and they will be uploaded in the future), a video showcases this huddling together the best. There’s strength in numbers here, but this is not a colony of insects as their is no queen to rule over them, and there doesn’t seem to be any strict hierarchy of individuals. They all gather food for themselves (even though they are more than capable of sharing). Regardless of that however, they must be some sort of social behavior going on otherwise these insects wouldn’t be tolerating each other. While their numbers are overwhelming here, the host tree doesn’t seem to be suffering which is a great thing. Nevertheless, if you’re concerned about swarming, watch for these insects, especially as Autumn and Winter draw closer. If they haven’t found refuge outside, they have been reported to venture into houses to wait out the winter, becoming active again around June or July.

Video was recorded on August 27, 2020 with a Google Pixel 4. Due to Tumblr’s video size restrictions, this video has been split in two. You can watch Part 1 here. You can also find this video on YouTube - in full - as of July 14, 2024.

Firebug (aggregation) - Pyrrhocoris apterus

Valentine’s Day may have been yesterday, but we can still celebrate the day after with pictures of some delightful insects. Or perhaps, a whole army of them nestled in the sunlight and in the roots of this tree! It’s never easy to choose a red insect for such a day. Having already used the Red Milkweed Beetle and the Red Admiral to celebrate, I thought this year I would go with a very prominent and common Red Bug. Literally, for this Red Bug is indeed a Red Bug of the family Pyrrhocoridae, some of which are called stainers. Many of the insects in this family have beautiful red patterns (sometimes on the underside) highlighted with black markings. Here we find many individuals with these patterns in the different stages of their life cycle. Most of these individuals appear to be sub-adults, waiting for their final molt into the “winged” adult. For the former, you can tell by the presence of black-colored wingbuds and a row of spots running down the abdomen of the Bug. Unfortunately things don’t really improve on the wing front (unless very lucky) into adulthood as Common Firebugs have reduced wings, compensated by a solid running speed. Although this aggregation looks intense for the afflicted tree, there is likely little danger to it as these insects mostly feed on seeds and fruit, and the tree seems otherwise healthy.

This tree is likely just a resting spot for these insects to settle in after the sun sets. There are plenty of nooks and crannies to hide in until the next day. They likely aggregate together for the safety in numbers while waiting to fully mature. After mating, most of them will likely go their separate ways to place eggs in optimal locations. Sometimes that means a warm house interior, but they’re just doing what they do, and while they can seem like pests, they aren’t dangerous at all. If you find any in your home or garden, I don’t recommend crushing them, for you see they don’t find each other by running around and bumping into one another. They communicate using scents and chemical markers in the form of pheromones to bring everyone within range to the safe haven. Squishing them may only release more of the pheromone and invite more guests and/or suitors to the party! It may also leave a nasty stain behind too, which exemplifies the “stainer” name. The insects will need to be relocated and the area rinsed of pheromones if you don’t want them coming back. Gardeners may consider using the hose to get rid of them, but I think these insects are alright and it’s both interesting and amazing to see such a level of aggregation (and teamwork to some extend) in insects outside of those in a colony or a gregarious swarm.

Hope you all had a wonderful Valentine’s Day!

Pictures were taken on August 27, 2020 with a Google Pixel 4. These insects can also be seen in 2 videos that were uploaded earlier.