<I>Neoseiulus </I> Predatory Mites / Home and Landscape / UC Statewide IPM Program (UC IPM)

Hosts or Prey

Spider mites (family Tetranychidae) primarily, but also mites in the families Tarsonemidae and Tydeidae, thrips, and other small arthropods

Identification

Neoseiulus species are tiny and recognizable only when viewed under magnification. However, because adults and nymphs move quickly and avoid direct sunlight, if the underside of leaves infested with spider mites is held in sunlight, the tiny, shiny body of Neoseiulus species or other predatory mites may be observed running rapidly across the leaf seeking shade. By comparison the plant-feeding mites are relatively sluggish.

Larvae are 6-legged, translucent to transparent, and relatively inactive. Adults and nymphs have 8 legs. Adults and nymphs are shiny and pear shaped to oval. Those of N. californicus are pale orange, peach-colored, or pink. Females are about 1/250 inch (0.1 mm) long and nymphs and adult males are somewhat smaller. The species can be reliably identified only by expert preparation of specimens and examination of microscopic characters.

The eggs are oblong and translucent to transparent. Neoseiulus eggs are about 1/400 inch (0.06 mm) long, which is larger than the round eggs of spider mites.

Life Cycle

Neoseiulus species hatch from an egg and develop through a six-legged larval stage and two eight-legged nymphal stages before maturing into adults. Adults and nymphs are predaceous and active searchers. Larvae generally do not feed or move much.

Adult females of N. californicus lay an average 2 eggs per day. They live for approximately 3 weeks when temperatures are warm. Adults and nymphs will feed on all stages of spider mites but prefer the eggs, larvae, and nymphs.

Habitat

Neoseiulus species can be the most common predatory mites in crops such as blackberry, raspberry, and strawberry. Neoseiulus californicus tolerates low humidities and high temperatures but prefers higher relative humidity. When arthropod prey is scarce it can survive on pollen.

Commercial Availability

At least N. californicus, N. cucumeris, and N. fallacis are commercially reared and sold for mass release to control pest mites. Neoseiulus californicus is sometimes released in greenhouse crops and strawberries. Twospotted spider mite, which infests numerous crop species, is the most common pest mite for which N. californicus is released.

To conserve resident natural enemies and any that are released

Control ants that attack natural enemies of various pests.
Grow flowering insectary plants to provide pollen to nourish the mites when prey is scarce.
Reduce dustiness that disrupts the activities of natural enemies (e.g., overhead irrigate or periodically hose off small plants).
Avoid the application of broad-spectrum, persistent insecticides and miticides for all pests because they are toxic to natural enemies.

See The Association of Natural Biocontrol Producers, Biological Control Organisms for Insects and Mites (PDF), Natural Enemy Releases for Biological Control of Crop Pests, and Protecting Natural Enemies and Pollinators for more information.

Species

Over 100 species of phytoseiid predatory mites occur in California. These include at least 25 Neoseiulus species, such as N. barkeri, N. brevispinus, N. californicus, N. cucumeris, and N. fallacis. Neoseiulus californicus appears to be the most abundant and widespread species of this genus in California.