The Pigeon tremex, Tremex columba, is a species of horntail, native to Eastern and Western North America. The females are larger than the males, with females growing to 25-30mm in length, and males about 20-25mm. The larvae feed on dead and dying trees such as beech, elm, maple, and oak.
Megarhyssa macrurus is the natural enemy of this species. It seeks out the larvae within the tunnels bored by this species. It then lays an egg next to the larva, which it then stings to paralyze it.
The Collaborative International Dictionary
Tremex \Tre"mex\, n. [NL.] (Zo["o]l.) A genus of large hymenopterous insects allied to the sawflies. The female lays her eggs in holes which she bores in the trunks of trees with her large and long ovipositor, and the larva bores in the wood. See Illust. of Horntail.
Note: The pigeon tremex ( Tremex columba), a common American species, infests the elm, pear, and other trees.