Description of the Pest
This fly breeds in overwatered conditions in association with algae. The adult is small (2 mm) and dark. The overall appearance is similar to a fruit fly; having short antennae and shorter legs than fungus gnats. The pair of dark wings has three white spots on each wing. When the fly is at rest, there appear to be five spots because the wings overlap.
Small, oblong eggs are laid in algal scum where larvae feed. Shore fly larvae have no distinct head capsule, and the body is opaque yellow, white, or brown. Both the dark brown pupa and the larva have a forked air tube at the rear end.
Large populations of shore flies can be a nuisance. Neither the adults nor larvae feed on plants. However, adult shore flies have been implicated in the spread of fungal spores in greenhouses. Fecal spots on leaves produced by resting adults can cause aesthetic damage to plants.
Biological control of shore flies has not been investigated.
Do not overwater. Control algae growing underneath benches, along irrigation lines, and in drainage areas.
Monitoring and Treatment Decisions
Yellow sticky cards placed in greenhouses will capture adult shore flies, see MONITORING WITH STICKY TRAPS. Because these flies do not directly feed on plants, treatment may not be essential unless there is a large nuisance population. Foggers and aerosols may be better at controlling adults than sprays.
Selected Materials Registered for Use on Greenhouse or Nursery Ornamentals
Read and follow the instructions on the label before using any pesticide. Before using a pesticide for the first time or on a new crop or cultivar, treat a few plants and check for phytotoxicity. Also consider pesticide resistance management and environmental impact.
|Manufacturer||REI1||Mode of action2||Comments|
(PT Pyrethrum TR)
|12||3/—||An aerosol. Also effective against adults.|
|insect growth regulator||A.||azadirachtin
|OHP||4||un||Must contact insect. Repeat applications as necessary. Only effective on larvae. Label permits low-volume application.|
(Citation 75 WP)
|Syngenta||12||17||Certification training required to use this product. Also effective against shorefly larvae.|
|Chemtura||12||15||Apply as spray or drench to top 2 inches of soil.|
|Valent||12||7C||Do not apply more than 2 times per cropping cycle or per 6 months.|
|Wellmark||4||7A||Apply prebloom. Also labeled for low volume use.|
|OHP||12||4A||Not to be used more than once every 16 weeks. Do not apply to soils that are water logged or saturated. Do not apply to bedding plants intended to be used as food crops.|
|(Marathon 60 WP)||As above. Apply only as a drench.|
(Orthene T, T&O Spray)
|Valent||24||1B||A number of chrysanthemum varieties have exhibited phytotoxic reactions. In greenhouse only labeled for use on anthurium, cacti, carnation, rose, orchids, some foliage plants, young poinsettia, and some varieties of chrysanthemum. Can stunt new growth in roses.|
(PT 1300 Orthene TR)
|24||1B||An aerosol for greenhouse use only.|
|Whitmire MicroGen||12||3||Check label. A fogger for greenhouse use only.|
|FMC||12||3||Also effective against adults. Label permits low-volume application.|
(Decathlon 20 WP)
|OHP||12||3||Also effective against adults. Label permits low-volume application.|
(Tame 2.4 EC Spray)
|Valent||24||3||Also effective against adults. Label permits low-volume application.|
|Wellmark||12||3||Also effective against adults. Label permits low-volume application. Also labeled as a cutting dip at 5 fl oz/100 gal.|
|FMC||12||3||Direct application to blooms may cause browning of petals. Marginal leaf burn may occur on salvia, diffenbachia, and pteris fern. Label permits low-volume application. Do not apply more than 2 lb a.i./acre/year.|
|1||Restricted entry interval (REI) is the number of hours (unless otherwise noted) from treatment until the treated area can be safely entered without protective clothing.|
|2||Rotate chemicals with a different mode-of-action Group number, and do not use products with the same mode-of-action Group number more than twice per season to help prevent development of resistance. For example, the organophosphates have a Group number of 1B; chemicals with a 1B Group number should be alternated with chemicals that have a Group number other than 1B. Mode of action Group numbers are assigned by IRAC (Insecticide Resistance Action Committee).|
|3||PBO = piperonyl butoxide|
|*||Restricted use pesticide. Permit required for purchase or use.|