Pigeon Horntail – Tremex columba

Pigeon Horntail – Tremex columba
Order Hymenoptera – Ants, Bees, Wasps and Sawflies
Symphyta – Sawflies, Horntails, and Wood Wasps
/ Family Siricidae (Horntails)
Live adult pigeon horntail photographed at the Morton Arboretum, Lisle, Illinois, USA.
Pigeon Horntail - Tremex columba
The Family Siricidae was until recently believed to be the sole living representative of the superfamily Siricoidea, a group well-represented in early Tertiary and Mesozoic times. Horntails are non-social wasps, unusual in that the larvae pupate inside dead wood, much like wood-boring beetle larvae. These larvae are often targets of wasps in the Family Ichneumonidae, which in turn drill into the wood to lay their eggs on them.

You can see one such wasp (Megarhyssa) drilling and laying eggs HERE.

The last tergite of the abdomen has a strong, projecting spike, thus giving the group its common name. The ovipositor is typically longer and also projects posteriorly, but it is not the source of the name. (Both are readily visible in the photograph below). A typical adult horntail is brown, blue or black with yellow parts in color, and may often reach up to 4 cm long. [2]

Pigeon Horntail - Tremex columba
This gal did not hang around for long. I was disappointed because this thing was huge, about 40mm!
Visible is the eponymous spike-like projection on the rear of the abdomen, above the ovipositor.


  1. Bugguide.net, "Pigeon Horntail"
  2. Wikipedia, “Horntail”

Order Hymenoptera: Bees, Wasps, & Ants

Hymenoptera (Latin for membrane wing) is a vast assemblage of insects second only to Coleoptera (beetles) in the number of described species. Hymenoptera number some 115,000 species – of which 18,000 live in North America. Hymenopterans inhabit a wide variety of habitats, and show an incredible diversity in size, behavior, structure and color.
Insects & Spiders | Bees & Wasps Index | Bees & Wasps