Target Pests: Fungus gnats (Bradysia spp.), Western flower thrips (Frankliniella occidentalis)
Description: Stratiolaelaps (Hypoaspis) is a native species of soil-dwelling mite, which feeds on small insects and mites (e.g. springtails, root mealybug crawlers, and spider mites). Adults are tan in color, less than 1 mm long (1/20th in.) and move rapidly over the soil surface. They live, eat, and reproduce in the soil medium and walkways on the greenhouse floor.
Use in Biological Control: Stratiolaelaps are used primarily to control young larvae of fungus gnats in the soil or planting media. They also help control soil stages of thrips and may account for up to 30% of thrips control. They do not control shore flies or moth flies, but will feed on other soil organisms, such as springtails and root mealybugs. They have been used successfully in bedding and potted plant production, seedling and cutting propagation, and poinsettia stock. Stratiolaelaps adapt well to the various growth media and capillary mats used in plant production, but do not survive freezing or flooding conditions.
Life Cycle: The complete life cycle takes about 18 days at 68°F (20°C). The sex ratio is an equal 1:1, females to males. Eggs hatch in 2-3 days into young nymphs, which are also fierce predators that consume eggs and small larvae. Each adult Stratiolaelaps will consume 1-5 prey per day. It can also survive as a scavenger in the absence of pests, feeding on algae and plant debris. Populations will naturally fluctuate throughout the growing season.
For Best Results: Do not mix predators into the growth media before potting plants because they do not survive. Apply Stratiolaelaps shortly within the first few weeks of planting and before fungus gnat levels reach more than 20 adults per trap, per week. To control high numbers of fungus gnats, use of Stratiolaelaps can be integrated with insect parasitic nematodes, which control the larval stage of fungus gnats.