Tip Top Bio-Control Technical Bulletin

Galendromus occidentalis
Western Predatory Mite

Target Pest:
All stages of Spider mites (not effective on eggs of European red mites).

Description:
G. occidentalis occurs naturally in Western North America, on many plants including Fruit trees, grapes, corn, cotton, ornamentals and strawberries. This predator has five life stages; egg, larva, protonymph, deutonymph and adult. It develops from egg to adult in 7-14 days depending on temperature. Females are predominate, usually 2:1 or 3:1. G. occidentalis does best in warm weather (80° to 110° F) and tolerates the low humidity common of valleys. It does not do well in cool coastal areas and will go into diapause in colder temperatures.

Release Rates:
Field crops: 2,000 - 5,000/acre at the first sign of mites.

A similar approach is recommended for other crops, but the timing will vary depending on the crop species and when Lygus populations increase.

Greenhouses: 2 per sq. ft. or 1 predator per 5 spider mites at the first sign of spider mites.

Later releases will require much higher numbers to be effective. In greenhouse, plants are needed to be maintained in as low as 30% relative humidity.

Product Information:
Highly perishable, the predators should be applied to the crop as soon as possible.

Strategic Considerations:
Some strains tolerate Guthion, Sevin, Sulfur and are developing tolerances to Pyrethroids. Field tolerance will vary with spray timing, application methods, weather and crop type. Avoid spraying one week before or after releasing predators. Some materials may be toxic for up to four weeks.