Margined blister beetles

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Garden Blogging

The tortoise beetle larvae have been chewing on the potatoes, and I finally got around to going out with a cup of soapy water to drown a few score.  They are little green worms with a brown shield on their backs. They build the shield out of their own shit, but luckily I'm not interested in eating them - only killing them.)

Among the harvestmen, wasps and dragonflies that hunt the foliage, I found a few long, black beetles hanging out among the stalks.  None of them were actively chewing on anything, but they didn't look very predatory either, so I read up on them.  

Margined blister beetles (as they are called) do chew on the foliage, but in fair exchange, since their larvae prey heavily on the eggs of grasshoppers and crickets - and those critters are all a-swarm and eating the plants.

The ten life stages of the blister beetle

The beetles are laced with the poison cantharidin, the active ingredient in the aphrodisiac Spanish Fly (which was always made up of pulverized blister beetles, not flies at all!)  If you can get the toxicity just right you can irritate the kidneys and urinary system enough to get a raging erection.  Unless you die of the poisoning instead.

Nowadays it's mostly grazing animals that get poisoned, and horses, cattle and sheep can die from ingesting a few of these potent insects.

None of us are likely to eat one (or crush one, which gets you nasty blisters on any exposed skin), so I'll just leave them be and count on their panoply of larvae to make omelettes of the local hopper eggs.