Colpotrochia trifasciata
(Cresson, 1864)
A small ichneumon in the Metopiinae, averaging 6-10 millimeters in body length. Females possess a very short used to lay in , particularly in the . The wasp develops inside the , consuming it without disrupting the caterpillar's until after it pupates; an wasp emerges from the host rather than a . One of two Colpotrochia recorded in Massachusetts, with a range extending from the Atlantic coast to barely west of the Mississippi River.

Pronunciation
How to pronounce Colpotrochia trifasciata: //ˌkɒlpəˈtroʊkiə ˌtraɪˌfæʃiˈeɪtə//
These audio files are automatically generated. While they are not always 100% accurate, they are a good starting point.
Identification
One of four North in the Colpotrochia, distinguished from C. crassipes by subtle morphological features best determined by examination. Members of Metopiinae can be distinguished from other subfamilies using the identification by Gavin Broad. The genus is characterized by the metopiine trait of laying in and emerging from host .
Images
Habitat
Found near outdoor lights at night in small towns, including on buildings such as police stations and post offices.
Distribution
Eastern North America, ranging from the Atlantic coast to barely west of the Mississippi River. Recorded in Massachusetts.
Seasonality
Active in June; observed at outdoor lights on June 23, 2009 in South Deerfield, Massachusetts.
Diet
The feeds on of ( ), developing internally as a .
Host Associations
Life Cycle
Female lays in using short ; consumes host from within without killing it immediately; emerges from host after caterpillar pupates.
Behavior
Attracted to outdoor artificial lights at night.
Ecological Role
of , contributing to regulation of .
Human Relevance
Potential agent for pests; of interest to hymenopterists and naturalists attracted to outdoor lighting for observation.
Similar Taxa
- Colpotrochia crassipesCo-occurs in Massachusetts; both in same with similar size range (6-10 mm) and biology; requires examination to distinguish.
- Other MetopiinaeShare the trait of emerging from rather than ; distinguished by -level and -level morphological characters.
Sources and further reading
- BugGuide
- GBIF taxonomy match
- iNaturalist taxon
- NCBI Taxonomy
- Catalogue of Life
- Bug Eric: April 2011
- Halloween ID challenge answer – Argiope trifasciata | Beetles In The Bush
- Bug Eric: Spider Sunday: Banded Argiope
- A truly disturbed garden spider | Beetles In The Bush
- Tiger Beetles at Florida’s “Road to Nowhere” | Beetles In The Bush