Wednesday, July 23, 2014

A taller tail

Wasps with "stingers" the size of hypodermic needles may sound like the stuff of nightmares, but they are quite real.

A giant ichneumon wasp (Megarhyssa nortoni quebecensis).
Happily, they are also quite harmless (at least to people).  Their needle-like "stingers" are used for laying eggs, not injecting venom.

A size comparison.
The ovipositors (literally, "egg placers") of giant ichneumons are so disproportionately long because of where their eggs need to go.  Giant ichneumons, just like their more modest relatives, are parasitoids of other insects.  The unusual challenge they face is that their hosts, the larvae of horntails (a.k.a. wood wasps), feed deep within wood.  To reach them, female giant ichneumons must pierce directly through the wood with their ovipositors.

The giant ichneumon searching for signs of larvae below.
However, first the wasps must complete another difficult task -- locating their hosts within the wood.  The wasp that I watched spent some time circling around and feeling the wood with its long antennae, but it appeared that there were no horntail larvae in reach.

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