Tergal-stroking
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Megarhyssa macrurus macrurus
giant ichneumon wasp
Megarhyssa macrurus macrurus is a North American giant ichneumon wasp and among the largest members of family Ichneumonidae. Females possess extremely long, slender ovipositors used to parasitize woodboring larvae of the pigeon horntail (Tremex columba) deep within tree trunks. Males aggregate on host trees and exhibit distinctive tergal stroking behavior, rubbing their abdomen tips against bark. This subspecies co-occurs with the larger M. atrata, with which it shares host resources through spatial partitioning based on ovipositor length differences.