Thread: Insects
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Old 2020-07-27, 14:10   #1
Dr Sardonicus
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Feb 2017

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This thread is for posts about insects -- member of the class Insecta (or Hexapoda). For ease of reference, I give other classes of terrestrial arthropods in case someone wants to start a subtopic on any of them.

Observations of beauty or behavior; interesting, painful, or scary encounters; things insects do that seem incomprehensible, are the sort of things I'm after.

Non-insect "creepy crawlies" in the phylum Arthropoda include spiders and ticks (class Arachnida); millipedes (subphylum Myriapoda, class Diplopoda), centipedes (subphylum Myriapoda, class Chilopoda), and "pillbugs," (subphylum Crustacea, class Malacostraca).

Insects live in a very different world than we do. They have eyes, but they are not like our eyes. Most insects have large "compound eyes," consisting of many individual receptors, each seeing a very small sector. They do not see much detail. But if something in its field of vision switches from one small sector to another, that is immediately detected, which makes insects extremely good at detecting things moving in their vicinity. (Insects also usually have some simple eyes, or "ocelli.") Many insects also have tiny hairs on their bodies which can sway with the slightest movement of air, which is thereby detected. This is why flies can often evade an approaching flyswatter.

Many insects do not hear much if anything, but many feel vibrations through their feet. Plant-dwelling insects can thus be able to communicate by making vibrations which are conducted through the plant.

Insects have "decentralized" nervous systems, local functions being governed by clusters of nerve cells called "ganglia." An insect can be decapitated, and still crawl around, work its wings, and breathe, which they do through orifices ("spiracles") in their abdomens. A decapitated wasp can continue to sting.

Insects do not seem to feel much pain, or to react to trauma as we might expect. An insect feeding on a plant might well keep placidly munching away, even as it is itself literally being eaten alive from behind.

The first specific insects I will post on are two large solitary "digger wasps," the Eastern Cicada Killer (Sphecius speciosus) and the Great Golden Digger Wasp (Sphex ichneumoneus).

Cicada Killers are among the largest of wasps. They are black with brown wings, and several large yellow markings on their abdomens. The males are territorial, and might buzz right in front of your face if you come too close to their territory, but they have no stingers. The females are larger, and have formidable stingers, but you would really have to work at it in order to get stung. They're only interested in finding a sunny location with well-drained soil (preferably near trees which harbor cicadas), digging their burrows (which can involve moving a hundred cubic inches (over 1600 cc's) of dirt), hunting down and paralyzing up to a dozen cicadas, laying an egg on each, and closing up the burrow. The helpless cicadas, which remain alive, insure a continued supply of fresh food for the wasp larvae.

As I was working on my future garden beds the other day, I noticed a hole and a pile of dirt next to one of the 2x4's I walk on when rain turns the dirt to mud. From diameter of the hole, I surmised I had a Cicada Killer in residence. And soon after, I actually saw it arrive at the burrow, bearing a cicada!

Cicada Killers often catch their prey on the wing. A successful hunt faces the female Cicada Killer with the task of getting her victim, which weighs two and a half times as much as she does, to her burrow. The choices are, (1) walk, dragging the load along the ground, and (2) gain some elevation, and aim for the burrow on a descending glide path. If it's a long distance, the wasp might climb, aim for the burrow, and and launch repeatedly. If she catches the cicada high enough in midair, and is close enough to the burrow, she might be able to make it directly.

The next day, I noticed another burrow, out in the open, about a foot away from the Cicada Killer's burrow. The new burrow was clearly the work of a Great Golden Digger Wasp, of which I had a goodly number in a front garden bed last year. Not as large as a Cicada Killer, but considerably longer and a bit wider than a paper wasp. They are black and orange, with dark wings and long orange legs. Wen landed, they frequently flick their wings. They sometimes visit flowers. Their prey is usually grasshoppers, katydids, and crickets. They aren't any more interested in us than Cicada Killers are. I saw my new resident land near its burrow (though without prey), and crawl in. I heard it buzzing its wings in the burrow. I'm not sure why it was doing that, but it sounded very similar to the sound bumblebees sometimes make while on flowers, when they buzz their wings without spreading them, which shakes pollen loose. Perhaps the wasp was increasing the diameter of its burrow. Perhaps it wasn't yet far enough along to begin stocking the larder.

I haven't yet been privileged to see a Great Golden Digger Wasp bring in a victim, but their task can't be any easier than the Cicada Killer's.

Last fiddled with by Dr Sardonicus on 2020-07-27 at 14:14 Reason: Insert missing right paren
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