Blackberry Knot Gall Wasp

Diastrophus nebulosus

A species of wasp in the Cynipidae family. Induces galls in blackberry stems: "Rounded or long stem swellings, sometimes with 4 or 5 deep longitudinal furrows, length 2 to 6 inches."
Taxonomy
KingdomAnimalia
DivisionArthropoda
ClassInsecta
OrderHymenoptera
FamilyCynipidae
GenusDiastrophus
SpeciesDiastrophus nebulosus