Thursday, May 19, 2016

Ichneumon Wasp Week

 Giant Ichneumon, Megarhyssa atrata - Andy Schiller
It was a big week for ichneumon wasps.  First Andy Schiller sent me this creature with the gorgeous tail and long antennae.  Many people will run away or swat away, thinking it has the world's largest stinger, but the only danger they present is to insect larvae.  Don't let those frail tails fool you.  They are ovipositors, used to drill deep into wood to lay their eggs on wood-boring insects.


This was identified as a Giant Ichneumon, Megarhyssa atrata.   The long ovipositor labels it as a female.  The ovipositors of some species will drill as much as two inches into wood, searching out insect larvae.  The wear and tear on the ovipositors must be tremendous and many have up to 10% of their ovipositor weight in metal in their cuticle to help them drill.

Limonethe maurator - Swearingen
Just as I completed this story above, Becky Swearingen sent me this beauty above, another ichneumon wasp.  There are various characteristics besides the female's ovipositor that distinguish Ichneumonidae from their stinging wasp cousins, most of which escape me.  One clue is their antennae which are generally at least over half their body length.  Many but not all species of the females have the long ovipositors.

L. maurator - Tim Lethbridge
The first species I guessed was Protichneumon grandis based on its coloration with the distinctive red abdomen.  After I had gone out on a limb on By-State Bugs, James Trager very gently sawed it off with the suggestion that it might be  Limonethe maurator and Becky confirmed it.  This too is an ichneumon wasp but in addition to the white band on the antennae and the red tummy, it has a distinct red hind femur versus the black leg of P. grandis.  

The family name Ichneumonidae has an interesting history.  According to Wikipedia, in medieval literature the "ichneumon" is the enemy of dragons, able to cover itself with mud, close its nostrils with its tail and attack and kill dragons.  It was able to kill the crocodile and the asp in the same manner.  Exactly what that has to do with laying parasitic eggs on beetle larvae or lepidoptera caterpillars escapes me, but it is an interesting story.

1 comment:

  1. I have wondered whence came "Ichneumon". Interesting. I can sorta see the analogy to the lives of ichneumonids.

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