More Urban Species: Acorn weevil

Acorn weevil, Curculio sp.

I caught this acorn weevil as it flew around the zoo library. There are no oak trees in there, so it must have hitched a ride on a human being. Just outside, however, stands the grand red oak forest that is Boston's Franklin Park. Strangely, this is the second time I've included a weevil caught indoors in this blog; likewise, when I led a reporter from The Weekly Dig around a few years ago, our first wildlife encounter was with a weevil. I don't think of weevils as being all that common (I don't think of weevils all that much at all), but they comprise the most numerous family* within the most numerous order (beetles) of all animals.

Acorn and nut weevils are numerous indeed, with at least 22 species feeding on seeds of oaks and others feeding on hickory, chestnut, and pecan tree seeds. Adults seek out acorns still on the tree, use their preposterous proboscis to drill through the nut shell, and feed on the meat inside. Females lay their eggs into these holes, and the legless larvae hatch and live within. The larva is somewhat protected by the seed shell, but a nut is no real obstacle to a squirrel, who will happily eat a fat weevil grub. One study showed that gray squirrels immediately consumed weevil-infested acorns 3/4 of the time they were available.

If the grub survives uneaten, it waits until the acorn falls, then chews its way out and digs into the soil to pupate. One genus of ant, Temnothorax, may move into the vacant nut to build its tiny nest. Conversations with an entomologist friend suggest that the pressure of weevil predation is a possible explanation for (or important factor influencing) year to year feast or famine acorn production.



*Wikipedia claims a controversy on this fact, suggesting that some experts assert that rove beetles rival weevils for numbers of species, but does not specify what experts those are.

(I'm a little worried I'll be remembered more for my awful fingers than for my contributions as a naturalist)

3:00 snapshot #1417

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3:00 snapshot #1418: dog phalluses, stunted by dryness

While doing my mushroom walk for the zoo staff, we came across a group of dog stinkhorns.

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