Arthropods--the most ubiquitous and diverse animals on Earth.

This sign is in South Africa, and it demonstrates the importance they place on dung beetles.

With the introduction of cattle into Australia during the late 19th century by Europeans the importance of the dung beetle was soon realized.

The dung beetle species in Australia we're not adapted to feed on the dung of cattle. Cattle dung without dung beetles may take as long as a year or more to break down and release the nutrients into the soil. Not only that, the dung dries into a 1 square foot object that blocks out sunlight to the plants underneath. If one head of cattle drops 12 cow pies per day, and there are 1 million head of cattle, and these compounds are not broken down for one year, that means that over the course of one year, 157 square miles of land will be covered with cow pies. If you extrapolate that to the 25 million head of cattle now in Australia 3,925 square miles of land would be covered with dung. That is an area about 63 miles squared.

Obviously, the land could not have supported that many cattle. The solution was to import dung beetles from Europe and Africa that were of a species adapted to the cattle dung. That solved the problem.

I admit it. I had no idea of the value of dung beetles. In fact, I was unaware of any value.

The really big ones take turns rolling the sun across the sky.

Everwhere, or just Australia?

Egypt for sure.

Many Arthropoda are microscopic.

I have two tickle - tongue trees, Zanthoxylem clava-herculis, which are in the citrus family. The giant swallowtail butterfly, Papillio cresphontes, which is common around here, lays its eggs on Citrus plants. I look forward to these butterflies laying eggs on my trees so I can watch the progress of the caterpillars. This year I had three, but none of them survived predation by wasps. Three isn't very many, and I attribute the shortage of butterflies to the spraying for West Nile virus.

From the picture you can see that the caterpillar resembles a big piece of bird poo. I suppose this is to just dissuade bird predation. Another defense mechanism they have is the osmeteria, these little, red horns that they evert with the slightest touch. I've read that they emit some sort of odorous, noxious gas to repel predators, namely predatory insects, but I've never been able to perceive any kind of odor emitting from these horns. At any rate the osmeteria are apparently not very effective because they've all been preyed upon by wasps.

I have had a few successes in prior years, though, and it's always a joy to see these bright, beautiful butterflies emerge and fly off.

It's amazing to me that such complex organisms can be so small.
Dust Mite:

This wasp is smaller than some single-celled organisms.

Megaphragma mymaripenne

I didn't realize that insects could be that small. Unless I'm wrong the length of that wasp is about 1/5 of a millimeter. What does something like that feed on? And consider the size of the egg.

I think that wasp in the photo is a juvenile. Probably only a bit larger than the egg it came from. I think it's a parasitic wasp, but I'm not sure what it's a parasite on.

I was going to put a picture of a Tardigrade out here, but they aren't technically arthropods (yet). They are still debating the classifications on Tardigrades.

The larva coming from the egg has got to be smaller. And unless I'm wrong there is no growth in the adult stage of insects.

I didn't research it very well, just grabbed the photo and read the caption. Feel free to dig into it

Ironclad beetle. I've seen about three of these around the Dallas area. A real rarity.

The hummingbird clearwing moth. When I first saw one of these I didn't know what it was. I didn't even know that it was a moth until a friend identified
it for me. The wings beat so fast it's like a blur.

Thats only true for insects with" complete metamorphosis" (those that go through egg, larva, pupae, adult). Insects with incomplete metamorphosis, beetles , locusts, katydids, roaches, etc. continue to grow . They develop via "instars" where each instar is a stage of growth where the insect develops as a virtual smaller copy of the next size up. (sorta like a snake, who sheds his skin when he gets to the next growth stage.)

We use arthropods (all kinds) from the opibinians of the bottom of the Cambrian through the middle Cambrian, to Trilobite (and other seafood) that left fossils at unique time delineations (in fact we often define that layer as an Olenellus or a Phacops horizon (the actual dates are only important when were locating a specific petroleum resource that is unique to the sediment in which that specific fossil lived. These time layers are spred all over the planet and the fossils often save us time in "correlating" one area from another.

There is a use for all the seafood and insect fossils. ALL early arthropods demonstrated only incomplete metamorphosis. We find trilobites of a single species in all different sizes. So they grow, they shed their "skins" and move on.

There were a very few arthropods that were as big as a car but these were only sea dwellers here the oxygenated water could flow through their bodies . Thats why lobsters have gills on each of their legs and spircles. On land, except for the Crboniferous period, inects were limited to a max size that conformed to the amount of oxygen that the air contained aince the air couldnt permeate throughout a bugs body if it were really huge. Now in the Carboniferous we saw bugs as big as amodel airplane because the O2 was quite high.

With the insects undergoing incomplete metamorphosis, such as the grasshoppers and bugs, etc., they go through three stages, egg, nymph, and adult. The nymphs resemble the adults but they don't have fully developed wings and they're not mature.

With the tiny and and near microscopic wasp in question, it was winged and, therefore, an adult and it wouldn't have gained any more size or growth. That was pretty amazing in itself, that something that small- the size of a paramecium-could be that complex. The wings were not membranous but more feathery like a thrip.