#insect aggregation

Brown Yucca Beetle - Caplothorax melanopterus

Just a relatively short post for today as these little seed-like crawlies have been thorough covered here in earlier posts. What can I say, they are a favorite of mine. The insect aggregations upon the summer's yucca blossoms continue, and the many individuals that gathered on the flowers have much to discuss...not really though. Its simply business as usual: emerge upon the yucca's stalks, have a bite or two, form mating pairs and place fresh batches of eggs such that they'll be able to feed within proximity to the plant's developing seeds. Unlike the last time these little insects were featured, there's no special occasion here, just more Beetles to enjoy. Despite all manner of tempting plants among their surroundings, these brown and black insects will spend nearly their entire lives upon the yucca stalk. The only times that one of these Beetles will ever be away from the precious yucca is if a predator catches them, they fall from the plant to the earth below, or when forming a pupal case in the soil (admittedly this isn't far from the plant itself) to metamorphose into adult form and wait for the next year's warm weather. Since this Sap-Feeding Beetle specie matures quickly, but chooses to remain dormant inside their secure pupal shells until spring (at minimum), this gives them a bit in common with many people of Ontario at the moment: with winter on our doorstep, we too eagerly await the eventual return of warmer weather. Unlike the Beetles, however, we cannot regulate our metabolisms to the minimum.

Red Aphids - Uroleucon sp.

The numerous red clone insects have returned to the blog with fresh images... but I forgot to identify the plants they were sprawled on. Regretfully, this makes an identification unlikely (for now) as these skittering Plant-Parasitic Bugs of the Uroleucon genus are associated with either a specific or somewhat specific range of host plants that they feed on during their lifecycle. Without identification of the plant, I can only speculate on which particular Aphid specie is featured on the blog today. As such, I will revisit the area later this year in the summer and see what I can find. If I'm being completely optimistic, perhaps the descendants of these Aphids will be found there as well! We'll see what the future brings, but for now, we look at the past and see what we can learn from these soft-bodied insects. On the identification front, there is some hope as the plants photographed here have sharp leaves and flowers with long, thin, yellow petals, giving them a strong resemblance to false sunflowers. Those particular flowers are the host of the Red Aphid known as U. obscuricaudatum, but it will take observation to confirm.

Similar to the last time this genus of Bugs was seen, there's also the possibility that this is an aggregation of U. pseudambrosiae or another specie among the nearly 100 Aphid species within the Uroleucon genus (except for U. erigeronense, since that one is clearly a green Aphid). In complete honestly, I'm also not sold on U. obscuricaudatum the more I look at the pictures. While I'll need better close-ups to confirm, the cauda for these Aphids isn't the right color. For these Aphids to be U. obscuricaudatum, their caudae (singular cauda) should be a curved with a dark color, but I'm not seeing that here and getting ahead of myself. In the case of Aphids, a cauda is the protrusion at the end of their abdomen. It's not a stinger or an ovipositor, but rather it's the final abdominal segment and it can be curved, knob or dome shaped. As for why Aphids have this protruding tail, its to aid them during their feeding. As it consumes plant juices, an Aphid will lean forward while feeding and will excrete honeydew out of its rear, and so it will flick the honeydew off of them using its cauda, ensuring the sticky fluid sits somewhere else. Other Aphids may instead kick away honeydew with their hindlegs, while other may simply allow it to drop upon the plant. It's possible that the lattermost strategy is useful for the Aphids who are tended to by the foraging worker Ants as it makes honeydew collection more simple.

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!

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.