Urophora stylata
From Bugwoodwiki
Author: Rachel Winston, Mark Schwarzlander. University of Idaho Extension.
Contents |
Hosts
bull thistle (Cirsium vulgare)
Description
Larvae are barrel-shaped, off-white in color, and have dark anal plates. They complete three instars and grow up to 5 mm long. Adults are light gray with a yellow head and brownish legs. Wings are clear and with a gray-brown “IV” shape the “V” being near the bottom of the wing. Adult males can be up to 5 mm long while females can be up to 7 mm.
Life Cycle
Overwintering larvae pupate in early summer when plants are bolting. Adults emerge throughout the summer and deposit eggs on immature buds. Hatching larvae burrow into seed heads and feed on seed producing tissue, inducing the formation of galls. There may be multiple galls per seed head. Third instar larvae overwinter within galls. There is one generation per year.
Impact
Larval feeding reduces seed production in bull thistle. Galls from larval feeding act as metabolic sinks, diverting resources away from normal plant development.
Availability
Available for redistributrion in the west, particularly in Oregon and Washington.
Comments
None
References
- 2011. Rachel Winston, Mark Schwarzlander. Noxious Weeds and their Biocontrol Agents: Cirsium thistles. University of Idaho Extension. USDA Forest Service-FHTET.
