Delia platura
Pest description and crop damage Adult flies are difficult to distinguish from other Delia species. D. platura adults are 0.2 inch long, gray or brown, and look like a small house fly. Eggs are not often seen, but larvae (maggots) and pupae are found in the soil near or within developing seedlings. Maggot will grow to 0.25 inch long with a creamy white colored tapered body and black hook-like mouthparts. Pupae are bronze colored, oval, and the size of oldest larvae. Larvae feed on spinach seeds or seedlings, resulting in stunted or missing plants. Minor feeding may cause notched or disformed cotyledons, and/or stunted plants.
Biology and life history In the PNW, there are generally three generation of D. platura per season. Pupae overwinter in the soil, and adults emerge around early to mid-April. The phenology of D. platura has been described with a Biofix of Jan 1, lower threshold of 39°F and upper threshold of 84.2°F (horizontal cutoff). First adult peaks occur at 360 degree-days. A real time model can be found at USpest.org.
Management-chemical control
- azadirachtin (Neemix 4.5) at 4 to 16 fl oz/A (0.012 to 0.049 lb ai/A). Apply in furrow or as soil drench. PHI 0 days. REI 4 hr. Washington Only.
- cyantraniliprole (Verimark) 5 to 13.5 fl. oz/A (0.065 to 0.176 lb ai/A). REI 4 hr. Do not apply a total of more than 0.4 lb ai/A per year for any cyantraniliprole product.
- thiamethoxam (Cruiser 70 WS) seed treatment. 0.12 mg ai/seed, up to 1,000,000 seeds per acre. Washington only.