tremex

from The Century Dictionary.

• noun A notable genus of hymenopterous insects, of the family Uroceridæ, separated from the typical genus Urocerus only by the venation of the wings.
• noun [lowercase] A horntail of this genus: as, the pigeon-tremex.

from the GNU version of the Collaborative International Dictionary of English.

• noun (Zoöl.) 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.