Encarsia formosa


Encarsia formosa is a tiny parasitic wasp that parasitizes whiteflies. It was the first biological control agent developed for use in greenhouses. Adults are black with yellow abdomen, less than 1 mm (1/20 inch) long (they do not sting). Larval stages live entirely inside immature whiteflies, which darken and turn black as the parasites develop inside. These insects are used to control greenhouse whitefly on greenhouse cucumbers, tomatoes, peppers and poinsettias and other plants grown in greenhouses. They control silverleaf/sweet potato whitefly using high release rates. Optimum conditions are temperatures over 20°C (68°F) and relative humidity 50-70%. When daytime temperatures are less than 18°C (64°F). Encarsia activity is sharply reduced, making them less effective. Encarsia should not be used if high whitefly populations are already established. 

LIFECYCLE: The complete life cycle takes about 28 days at 21°C (70°F). Temperature affects developmental rate; for example, larval development takes 15 days at 25°C (77°F) and 45 days at 15°C (59°F). Encarsia populations are all female (males sometimes occur but they are not functional). Eggs are laid in 2-week-old whitefly scales (second and third whitefly larval stages), one egg per whitefly. Most Encarsia are female and each lays up 10 eggs per day for an average of 200 eggs. Larvae develop inside the whitefly scale for 10 days (at 20° - 25°C). They pupate for another 10 days, then adults emerge by chewing a hole in the top of the scale. Adults are most active for about 10 days, although they can live up to 30 days. 

RELEASE INSTRUCTIONS: Encarsia pupae are sold glued onto cards. It is important to hang the cards from lower leaves in the shade as Encarsia tend to fly upward; avoid wetting them while watering. If there are hanging baskets some cards must be placed on the baskets, as well as on infected plants. Adults will emerge from the pupae over a period of 1-2 weeks at 20° -25°C. Small emergence holes in the pupae are visible using a 5-10X lens and indicate that the parasite has emerged. If necessary, the Encarsia pupae can be held for up to 2 weeks at 5°-10°C (40°-50°F), however the percentage of emergence will decrease with time. Once you have made it home with your Encarsia, you must place the cards with their eggs in the infestation zone immediately upon receiving your package. Hang the individual cards or strips in shaded locations so they are evenly distributed throughout the infested area. Whitefly parasites will emerge from the black host eggs over a period of 2 weeks and will immediately seek out and parasitize immature whitefly. Release at a rate of 2-4 whitefly parasites per sq. ft. for four consecutive weeks. Release when temperatures are cooler. 

RELEASE RATES: Note - These rates are for preventative control only, multiple releases and/or higher quantities are necessary for heavier infestations. 


500 Insects (Eggs) 250 sq. ft.
1,000 Insects (Eggs) 500 sq. ft.