Field Identification
Tephritid relative of apple maggot that stings walnut husks, causing dark sunken stings, stuck hulls that stain the shell, and premature drop. Larvae feed in the husk, not the kernel—damage is market grade and handler annoyance.
Adults have patterned wings with clear apical spots; larvae are white maggots in the husk in late summer. Emergence tracks growing degree-days after spring soil warming.
How to Deal With It
Organic Control Methods
Spinosad or kaolin clay targeted at adult flies during the pre-oviposition window; repeat after rain washes kaolin—organic programs demand obsessive timing versus calendar sprays.
Parasitoid guilds on Rhagoletis spp. are modest; generalist predators pick off adults at feeding sites.
Destroy fallen husks promptly; remove alternate hosts if any exist nearby; coordinate neighborhood sanitation because adults fly orchard to orchard.
Yellow sticky spheres or panels baited with ammonium carbonate for monitoring and some mass capture.
Track biofix with traps; treat only when catches cross regional thresholds.
Let Nature Handle It
Natural Enemies
- Parasitic Wasps
- Robber Flies
- Spiders