Natural Enemies Gallery

Spider Mite Destroyer

Hosts or Prey

Plant-feeding spider mites (family Tetranychidae)

Identification

The adult spider mite destroyer is a lady beetle, sometimes called a ladybug or ladybird beetle. It is black and about 1/16 inch (1.5 mm) long. It can appear grayish because adults have a finely pitted surface covered with minute, pale hairs. The adult is dome-shaped (convex) on top, flat on bottom, and oval when viewed from above.

The eggs are oval and about 1/64 inch (0.4 mm) long. They are pale yellow to white when laid then turn gray and become blackish before hatching.

The larva is oblong and dark brown to gray when young. It is covered with numerous, minute, branched hairs. As the larva matures it becomes reddish, at first on the edges of the body; just prior to pupation the entire larva turns reddish.

Pupae are oblong or oval when viewed from above and flattened when viewed from the side. They are covered with tiny, pale hairs and depending on maturity vary in color from black to brown, gray, or reddish.

Life Cycle

Lady beetles develop through 4 life stages: egg, larva, pupa, and adult. Adult females lay eggs singly, scattered among spider mite colonies. Females typically lay about 100 to 200 eggs during their lifespan of 1 to 2 months. After hatching from an egg, Stethorus larvae develop through 4 increasingly larger instars. During warm temperatures the spider mite destroyer can complete egg to adult development in 3 to 4 weeks.

Habitat

Spider mite destroyers are specialized predators, feeding on all stages of spider mites. Stethorus adults and larvae each can consume up to 75 mites per day. Once mite populations have developed to moderate levels, Stethorus is especially important in reducing their abundance. Adult Stethorus readily fly and are highly effective at finding where mites are abundant, and then laying eggs there and voraciously feeding on the mites.

Stethorus eggs are laid singly on their sides and adhere tightly to the leaf. Females lay 1 to 10 eggs per leaf, depending on mite density. Most Stethorus eggs are laid on the underside of the leaf, alongside major veins.

Species

Seven or more Stethorus species occur in the United States. They are all predators of spider mites. The most common are Stethorus picipes, sometimes called Stethorus punctum picipes, in California and Stethorus punctum punctum in the Eastern United States, both of which are commonly called spider mite destroyer. Stethorus picipes is the only Stethorus species reported in California.

More Information

Scientific classification:

  • Phylum: Arthropoda
  • Class: Insecta
  • Order: Coleoptera
  • Family: Coccinellidae
Adult spider mite destroyer, Stethorus picipes, feeding on a mite.
Adult spider mite destroyer, Stethorus picipes, feeding on a mite. Credit: Jack Kelly Clark, UC IPM Program
Adult spider mite destroyer, Stethorus picipes.
Adult spider mite destroyer, Stethorus picipes. Credit: Jack Kelly Clark, UC IPM Program
Pale, oblong egg of spider mite destroyer, Stethorus picipes, next to dark, spherical eggs of a spider mite.
Pale, oblong egg of spider mite destroyer, Stethorus picipes, next to dark, spherical eggs of a spider mite. Credit: Jack Kelly Clark, UC IPM Program
Larva of the spider mite destroyer, Stethorus picipes, feeding on twospotted spider mites, Tetranychus urticae.
Larva of the spider mite destroyer, Stethorus picipes, feeding on twospotted spider mites, Tetranychus urticae. Credit: Jack Kelly Clark, UC IPM Program
Pupa of the spider mite destroyer, Stethorus picipes.
Pupa of the spider mite destroyer, Stethorus picipes. Credit: Jack Kelly Clark, UC IPM Program
Relative size of pupa, last instar, and adult spider mite destroyer, Stethorus picipes.
Relative size of pupa, last instar, and adult spider mite destroyer, Stethorus picipes. Credit: see large image