Biomedical Ephemera, or: A Frog for Your Boils

Ammophila urnaria acquiring caterpillar to stock egg burrow

The thread-waisted wasps are all known as "predatory" wasps, and are classified as "parasitoids". Females dig a burrow with several chambers, and collect caterpillars to fill each chamber. They then lay an egg on the top caterpillar, and permanently seal the burrow. This is generally repeated several times, with between 2 and 13 burrows filled with caterpillars.

Thing is...the caterpillars aren't dead. They have to manage to not become dessicated or decayed for the entire period between the laying of the egg and the pupation of the juvenile, a period sometimes longer than several weeks, during the summer. The female wasp stings the caterpillar around the abdomen with a nerve-destroying paralytic poison, and while paralyzed, the caterpillar body automatically utilizes the stored fat (normally used to metamorphose into a moth or butterfly) to stay alive and not rot. Occasionally the caterpillars have been found to die, or not be paralyzed the entire period prior to their becoming food, but the female wasp has an extremely efficacious venom. The caterpillars almost always remain in their chamber until they're eaten alive by the juvenile.

After it pupates, the adult wasp is capable of digging out of the burrow from the inside.

Wasps, Social and Solitary. George Peckham and Elizabeth Peckham, 1905.

Hyperparasitism: Parasites that are parasitic to parasites!

The wonderful world of entomology - parasites within parasitoids all over the place! Though parasites are found throughout the natural world, insects have some of the most interesting examples found between (and sometimes within) the families of the order, including many hyperparasites.

At top, you can see the parasitoid (a parasite that generally consumes or intentionally leads to the death of the host - long-term survival within the host is not the goal) burrowing-wasp parasitizing the rhinoceros beetle larva. Once the female burrowing-wasp "smells" out the location of the larva, she burrows down to it and lays an egg on the body. After her egg hatches, it feeds on the larva. When the beetle larva is consumed, the burrowing-wasp pupates, and forms a chrysalis underground. After metamorphosis, it digs its way up and out, and feeds on pollen or nectar while searching for a mate.

But the insect world does not always let one get away with that sort of parasitoid behavior for free! Many members of the Hymenoptera, including the burrowing-wasps, are in turn parasitized by Strepsiptera, formerly known as the "twisted-winged parasites". This parasitism of parasites (or parasitoids) is known as hyperparasitism, and is mostly found in entomophagous (insect-eating) insects.

As larva, Strepsiptera are free-roaming insects, looking for a host. Once the appropriate host is found, the larvae will enter the insect (using various mechanisms) and take up residence in its abdomen, as can be seen in the image on the bottom-right. Both sexes go through the last instars (moults) of their larval stage within the host. After this stage, there is a vast difference between the females and the males - the males pupate, go through a complete metamorphosis, and emerge from the host as adults (of course, killing the host in the process). The females become neotenous adults (adults capable of reproduction, but with juvenile forms - axolotls are another example), and stay within the host for their entire life. The male mates with them while they're within the host, and their eggs hatch inside their bodies.

Fun fact: When the Strepsiptera larvae emerge from the host, the brood canal they come out of is generally at the top of the abdomen, just below the head, so the host ends up having babies coming out of its "neck". This doesn't kill them, and some hosts end up sustaining three or more broods of its parasite. Cool stuff!

Top: Burrowing-wasp parasitizing rhinoceros beetle. Marvels of Insect Life. Edward Step, 1916. Bottom Right: Adult male Strepsipteran (Stylos dalii), free of host. British Entomology. John Curtis, 1823-1840. Bottom Left: Adult female Strepsipteran and adult female Strepsipteran within host. Applied Entomology. H.T. Fernald, 1921. 

Compound Eyes of Insects

A single unit of a compound eye is an ommatidia. Each ommatidia consists of the outward lens, the transparent crystalline cone below that, the visual cells (arranged in a radial pattern, sorta like the sections of an orange), and the pigment cells (which separate the ommatidia).

Some insects, like the dragonfly, can have over 20,000 lenses in a single eye.

The Animal Kingdom, Arranged After its Organization. Baron Cuvier, 1854 (posthumous publication).

The Decorative Home Apiary

"How doth the little busy bee,    improve each shining hour; Gathering honey all the day,    From ev'ry opening flower."

"Mama, mama! Rufus is eating uncle's bees!"

The American Bee Keeper's Manual. T. B. Miner, 1849.

Indian Hymenoptera

These are examples of some of the leafcutter bees (Megachile) of India. You can see the leaf-stuffed nest of one species of leafcutter at the top of the plate, and the cut leaves of a rose bush at the bottom right of the plate.

Transactions of the Zoological Society of London, vol VII. 1872.

"New Yunan Insects"

1. Caeneressa diaphana 2. Amata sperbius 3. Syntomoides imanon 4. Amata grotei 5. Amata sladenei 6. Vespa mandarinia bellona [Asian Giant Hornet] 7. Apis laboriosiosa 8. Bombus impetuosus

Proceedings of the Zoological Society of London. 1871.