DESCRIPTION
Adults are tawny brown, 4 to 6 mm long (slightly smaller than a housefly) with large green eyes, banded wings and a yellow spot of its back. Headless larvae are white when young, turning yellow as it matures, up to 13 mm in length.

DAMAGE
Larvae tunnel into green walnut husks, producing a slimy black mush that stains the walnut shell (does not affect nut). Occasionally peaches grown close to walnuts will be attacked. Larvae feed internally in peach flesh.

LIFE CYCLE
Overwinters as pupa in soil beneath walnut trees. Adults emerge from July to September and mate 8 days after emergence. Eggs hatch in 5 days and maggots feed for 3 to 5 weeks. Mature larvae exit the fruit and drop to the soil to pupate where they remain at least one year, and sometimes up to 3 or 4 years. There is one generation per year.

CONTROLS
• Monitor adults using sticky yellow board traps. Hang traps at least 6 feet off the ground in a shady part of the tree. You can also hang a smooth lime green ball the size of a tennis ball coated in Tanglefoot.
• Once a significant number of adults are detected, usually early to mid-August, apply contact pesticide within 10 days to prevent egg laying. Repeat 3 to 4 weeks later. Do not apply after husks split.
• Pick off damaged fruit if practical. Remove fallen infected fruit and submerge in a bucket of water to drown remaining maggots.
• Keep a pest journal for next year, noting severity of damage, controls used, and when you first noticed pest in relation to fruit emergence or bloom time of another plant.

PESTICIDES
• Chemical-Malathion or Ambush at label rates.
• Alternative-Safer’s Soap, Trounce or Pyrethrin at label rates.
• Adding molasses significantly increases effectiveness of pesticides. (to print, right-click on this page)