Tip Top Bio-Control Technical Bulletin
Feltiella acarisuga are destroyers of spider mites and biological control for tomatoes, cucumbers and other greenhouse crops where spider mite infestations are a problem.
Feltiella acarisuga are tiny yellowish maggots which will prey on spider mites immediately after hatching. After about a week of eating spider mites, mature maggots begin to pupate, forming cocoons adjacent to leaf veins that yield new adults within about six to seven days. All stages of the insect should be visible in the greenhouse within 2 to 3 weeks of application. Feltiella will persist in the greenhouse until the spider mite infestation is controlled, after which time they will die off.
Feltiella are sold as pupae (small, white cocoons) on paper and packaged in units of 250. The average emergence rate of adults from the pupal stage is approximately 90%, over 300 cocoons are packaged in each tub to ensure a yield of 250 adults. To use a tub, all the grower needs to do is remove the lid and leave the tub in the shade in the vicinity of spider mite outbreak. Adult midges will emerge over the course of three to four days, mate and lay eggs on the leaves of mite-infested crops.
A tub of 250 Feltiella cocoons should be applied for localized outbreak of spider mites. Widespread and severe infestations need a minimum of four tubs (1000 cocoons) per acre for six consecutive weeks, in order to establish an effective midge population quickly.
Adults die after four to six days and are replaced by a new batch of larvae which hatch two days after eggs are laid.
The number of midges will increase in response to increases in prey numbers and can search out isolated spider mite outbreaks from a distance. Feltiella works best on crops with hairy leaves and stems such as cucumbers and tomatoes. They have been shown to work quite effectively on tomatoes where Phytoseiulus persimilis mites are ineffective. Feltiella and P. persimilis can co-exist at high population densities and can be used together for effective spider mite control. Feltiella are recommended for prevention of spider mite outbreaks. Since they cannot survive in the absence of their prey, these midges should be released only after a spider mite problem has truly been detected.