Scale Predatory <I>Chilocorus Kuwanae</i> Lady Beetle / Home and Landscape / UC Statewide IPM Program (UC IPM)

Hosts or Prey

Scale insects, especially armored scales

Identification

The adult lady beetle (ladybug or ladybird beetle) is 1/8 to 1/5 inch (4–5 mm) long. It is black with two red spots on the wing covers. The bottom margin of the wing covers flares outwards ridgelike.

Eggs are oblong and bright red. They occur singly or in a group of a few in bark crevices or laid under scale insects or their cover.

Larvae are brown to dark pinkish with numerous, black, branched spines. The mature larva is about 1/5 inch (5 mm) long. Pupae are oblong and black and brown. They occur within the spiny skin of the last instar glued on plants.

Lookalikes

There is a form of the adult ashy gray lady beetle (O. v-nigrum) that is black with two red spots on the wing covers. However, adults of ashy gray lady beetle have pale (gray or whitish) coloration on both the head and thorax that is lacking on C. kuwanae and its other lookalikes, Axion and Chilocorus species. Larvae of ashy gray lady beetle have a smooth surface and lack the numerous, branched spines that cover larvae of Axion and Chilocorus species.

Other California lady beetles that are black with two red spots are Axion plagiatum, Chilocorus cacti, C. fraternus, and twicestabbed lady beetle (C. orbus). However, in comparison to these species the spots on C. kuwanae are somewhat rectangular (not smoothly roundish), deeply red (not orangish), and occur in the middle or slightly toward the rear of the wing covers. Also the bottom sides of the wing covers on C. kuwanae are more strongly flared outwards in comparison with Axion and the other Chilocorus species. Expert dissection and examination of male genitalia may be needed to reliably distinguish the species.

Life Cycle

Lady beetles develop through 4 life stages: egg, larva, pupa, and adult. Adult females lay eggs singly or in a group of a few. If nectar and pollen are available as nourishment an adult female can live about 10 weeks and lay about 200 eggs.

After hatching, larvae grow through 4 increasingly larger instars. Each larva consumes over 100 scales during its development time of about 3 weeks during warm weather. Larvae commonly remove the scale cover or overturn the body to feed on its fleshy parts. Mature larvae (prepupae) commonly pupate in groups openly on bark.

Overwintering is as adults in protected places. Where winters are mild and scales are present the adults can be active anytime temperatures exceed about 50°F. Egg to reproductive adult development time is about 1 month when temperatures are warm. Chilocorus kuwanae has at least 3 generations per year.

Habitat

Chilocorus kuwanae occurs mostly on woody species including in landscape trees and shrubs, tree crops, and wildlands where plants are infested with scales. It was imported by U.S. Department of Agriculture from China, Korea, and Pakistan several times from 1895 through the 1980s. It was released in numerous states including California as part of a classical biological control program to control scales including California red scale, euonymus scale, and San Jose scale. Chilocorus kuwanae is now established in California and much of the United States.

To improve biological control

Control ants because they attack lady beetles and other natural enemies.
Grow flowering insectary plants to provide nectar and pollen to feed adult natural enemies.
Reduce dustiness that disrupts the activities of natural enemies (e.g., periodically hose off small plants).
Avoid the application of broad-spectrum, persistent insecticides for all pests because they are toxic to natural enemies.

See Protecting Natural Enemies and Pollinators for more information.

Species

At least 191 species of lady beetles occur in California. These include at least 5 Chilocorus species, the 4 named above and C. bipustulatus. All Chilocorus are predators mostly on scale insects. Chilocorus kuwanae is sometimes called Kuwana's lady beetle.