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How to Manage Pests

UC Pest Management Guidelines

| More pests | More crops | About guidelines |

Adult shore flies resting on a leaf.

Floriculture and Ornamental Nurseries

Shore Fly

Scientific name: Scatella stagnalis

(Reviewed 3/09, updated 3/09)

In this Guideline:

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.

DAMAGE

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 causen aesthetic damage to plants.

MANAGEMENT

Biological Control
Biological control of shore flies has not been investigated.

Cultural Control
Do not overwater. Control algae growing underneath benches, along irrigation lines, and in drainage areas with hydrated lime.

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.

TREATMENT

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.

Class   Pesticide
(commercial name) 		Manufacturer R.E.I.1 Mode of action2 Comments
botanical A. pyrethrin/PBO3
(PT Pyrethrum TR) 		Whitmire
MicroGen 		12 3 An aerosol. Also effective against adults.
  B. pyrethrin/rotenone
(Pyrellin EC) 		Webb Wright 12 3 Also effective against adults.
insect growth regulator A. azadirachtin
(Azatin XL) 		OHP 4 26 Must contact insect. Repeat applications as necessary. Only effective on larvae. Label permits low-volume application.
  B. cyromazine
(Citation 75 WP) 		Syngenta 12 17 Certification training required to use this product. Also effective against shorefly larvae.
  C. diflubenzuron
(Adept 25WP) 		Chemtura 12 15 Apply as spray or drench to top 2 inches of soil.
  D. pyriproxyfen
(Distance) 		Valent 12 7C Do not apply more than 2 times per cropping cycle or per 6 months.
  E. s-kinoprene
(Enstar II) 		Wellmark 4 7A Apply prebloom. Also labeled for low volume use.
neonicotinoid A. imidacloprid
(Marathon 1G) 		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.
organophosphate A. acephate
(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.
  B. acephate
(PT 1300 Orthene TR) 		Whitmire
MicroGen 		24 1B An aerosol for greenhouse use only.
  C. chlorpyrifos*
(PT DuraGuard ME) 		Whitmire
MicroGen 		24 1B  
pyrethroid A. bifenthrin
(Attain TR) 		Whitmire MicroGen 12 3 Check label. A fogger for greenhouse use only.
  B. bifenthrin*
(Talstar Flowable) 		FMC 12 3 Also effective against adults. Label permits low-volume application.
  C. cyfluthrin
(Decathlon 20 WP) 		OHP 12 3 Also effective against adults. Label permits low-volume application.
  D. fenpropathrin*
(Tame 2.4 EC Spray) 		Valent 24 3 Also effective against adults. Label permits low-volume application.
  E. fluvalinate
(Mavrik Aquaflow) 		Wellmark 12 3 Also effective against adults. Label permits low-volume application. Also labeled as a cutting dip at 5 fl oz/100 gal.
  F. permethrin
(Astro) 		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 (R.E.I.) 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). For additional information, see their Web site at http://www.irac-online.org/.
3 PBO = piperonyl butoxide
* Restricted use pesticide. Permit required for purchase or use.

[Precautions]

PUBLICATION

[UC Peer Reviewed]

UC IPM Pest Management Guidelines: Floriculture and Ornamental Nurseries
UC ANR Publication 3392
Insects and Mites
J. A. Bethke, Entomology, UC Riverside
Acknowledgment for contributions to Insects and Mites:
K. L. Robb, UC Cooperative Extension, San Diego County
H. S. Costa, Entomology, UC Riverside
R. S. Cowles, Connecticut Agricultural Experiment Station, Windsor, CT
M. P. Parrella, Entomology, UC Davis

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Statewide IPM Program, Agriculture and Natural Resources, University of California
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