Three inch (7 cm) long herbivorous wasps flew through the landscapes of what is now British Columbia some 53 million years ago, according to Dr Alexandr Rasnitsyn of the Natural History Museum, London, and Dr Bruce Archibald of the Royal B.C. Museum and Simon Fraser University.
Ypresiosirex orthosemos, photographs and drawing; abbreviations: cr – cornus, an – anus. Scale bar – 1 cm. Image credit: S. Bruce Archibald / Alexandr P. Rasnitsyn.
The fossilized remains of a previously unknown horntail wood-wasp species were discovered in the McAbee Fossil Beds near Cache Creek, British Columbia, Canada.
According to a report published last month in the journal Canadian Entomologist, the specimen – named Ypresiosirex orthosemos – also represents a completely new genus.
The fossil horntail wood-wasp resembles its modern relatives and is in remarkable condition. In terms of size it is gigantic, measuring almost 3 inches.
“Horntail wood-wasps are forest pests today: their young bore tunnels through wood to create gardens in which they grow the fungus that they eat,” Dr Archibald and Dr Rasnitsyn said.
“A secretion the wasp then produces weakens the tree’s immune system, and the fungus emits plant poisons, eventually killing it.”
“All of the elements that their modern relatives prefer today were in place in our region by the time of Ypresiosirex orthosemos,” they said.
“Many of the trees and other plants that modern horntail wasp young burrow in have been found as fossils in the same locations as the ancient wasps, including fir, pine, spruce, hemlock, sequoia, cedar and possibly juniper, as well as a number of their preferred flowering plants such as maple, beech, hickory, ash, poplar, elm, and possibly oak.”
“The climate was right for these insects, too,” Dr Archibald and Dr Rasnitsyn said. “Although the ancient forest grew during a phase of Earth’s history when much of the globe experienced tropical heat, because the southern interior of British Columbia was an upland of some significant elevation, the average temperature in the McAbee forest would have been much like that of modern Vancouver, temperatures that wasps find agreeable.”
“The major difference is that the ancient winters were much milder, with few, if any, frost days across the region.”
In the same paper, Dr Archibald and Dr Rasnitsyn also described two new genera and three new species of sawflies from Republic, Washington, and McAbee, British Columbia.
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S. Bruce Archibald & Alexandr P. Rasnitsyn. New early Eocene Siricomorpha (Hymenoptera: Symphyta: Pamphiliidae, Siricidae, Cephidae) from the Okanagan Highlands, western North America. Canadian Entomologist, published online October 27, 2015; doi: 10.4039/tce.2015.55
