A giant ichneumon wasp (Megarhyssa macrurus) uses her extremely long ovipositor to drill into a dead maple tree. Megarhyssa includes species with the longest ovipositors of any insect (up to 11 cm in M. macrurus and up to 14 cm in its cousin M. atrata), which also technically gives them the longest total length of any hymenopteran insect. The ovipositor is used to pierce deep into dead or dying trees to lay eggs on the larvae of a large wood-boring sawfly (Tremex columba).
Her ovipositor acts not only as a drill but as a sensory organ, and is highly sensitive to vibrations in the wood made by the sawfly larvae. Note how the translucent membranes of her abdomen stretch as she applies pressure by curling the base of the ovipositor, then retract when she withdraws to search for a different spot.
(Massachusetts, July 2025)
