The Horntail is a small, non-stinging wasp with a long body. The female Horntail has a long appendage from the posterior of its abdomen called an ovipositor. Since we’re used to thinking of wasps as stinging pests it is common to think it is a stinger. The female uses her ovipositor to place her eggs deep inside decaying or diseased trees where her young will hatch and feed on the decaying wood.
The Horntail often finds its way into our homes when the female lays her eggs on new or old wood used for construction. If the wood is not treated after eggs are deposited, the young develop in the wood for several years and then emerge, well after construction is completed.
Dark brown with yellow
If Horntails emerge from new construction the wood may need to be replaced if the holes and tunnels left behind are extensive or cosmetically unappealing, but no further treatment is needed. The Horntails will not return to the wood again.
Horntail wasps are most active in summer and fall.