Extreme-morphology
Guides
Megarhyssa atrata
Black Giant Ichneumonid Wasp
Megarhyssa atrata is the largest known hymenopteran parasitoid, with females possessing an ovipositor that can exceed 130 mm—longer than any other arthropod genital apparatus. The species is primarily black with a yellow head and legs, and lacks the reddish-orange markings found in congeners. It parasitizes the larvae of the pigeon horntail (Tremex columba) deep within decaying hardwood, using remarkable wood-penetrating adaptations. Males aggregate at emergence sites and exhibit distinctive "tergal stroking" behavior, rubbing their abdomen tips against bark.