Whitefly Predatory <I>Delphastus</i> Lady Beetles / Home and Landscape / UC Statewide IPM Program (UC IPM)

Hosts or Prey

Identification

At least three Delphastus species lady beetles (ladybugs or ladybird beetles) occur in California and their appearance and biology are similar. As D. catalinae (commonly misidentified as D. pusillus) is the well-studied species and the most common Delphastus species in California, it is the focus of this webpage.

The Delphastus adult is circular when viewed from above, dome shaped (convex) when viewed from the side, and about 1/16 inch (1.5 mm) long. It has a black to dark brown head and thorax and black eyes. Its appendages are orangish or yellowish brown and the head is reddish or yellowish brown.

The oval eggs are pale yellow to whitish and about 1/100 inch (0.2 mm) long. They occur glued on their end and in a loose cluster among colonies of whiteflies. Larvae are pale yellow with distinct segments and are covered with fine, short hairs. Larvae are about 1/12 inch (2 mm) long when mature.

The oval to spherical pupae are about 1/16 inch (1.5 mm) long and covered with fine hairs. Pupae initially are pale yellow to whitish. They darken as they age and develop distinct appendages folded against the body.

Life Cycle

Lady beetles develop through 4 life stages: egg, larva, pupa, and adult. Adult females live for about 2 months during which each beetle lays 200 to 300 eggs. After hatching larvae develop through 4 increasingly larger instars.

Delphastus catalinae adults, eggs, and larvae are found in colonies of whiteflies, which generally occur on the underside of leaves. Pupae can also occur on the underside of leaves commonly along leaf veins. But sometimes the mature larvae (prepupae) move to a lower portion of the plant to pupate in a protected location.

Adults and larvae of D. catalinae prey on all stages of whiteflies but prefer the eggs and nymphs. An adult eats about 150 whitefly eggs or 12 large nymphs each day. To be able to oviposit a female beetle must consume on average at least 100 whitefly eggs per day. A larva consumes about 1,000 eggs or 700 nymphs of whiteflies during its development. Adults and larvae also consume honeydew, which increases beetle longevity.

The adults and larvae of D. catalinae avoid feeding on parasitized whitefly nymphs. This lady beetle is compatible with wasps parasitic on whiteflies, such as Encarsia formosa and Encarsia pergandiella.

Development time from an egg to a reproductive adult is about 3 weeks when temperatures average 77ºF. Delphastus catalinae has several generations per year.

Habitat

Delphastus catalinae can occur in field and tree crops, gardens, landscapes, and wildlands wherever whiteflies occur. Its economically important prey includes greenhouse whitefly, silverleaf whitefly, sweetpotato whitefly, and woolly whitefly.

Commercial Availability

Delphastus catalinae is available from commercial insectaries, which may name it D. pusillus. Releases of this beetle have primarily been on whitefly infested greenhouse crops.

To conserve resident natural enemies and any that are released

Control ants because they attack lady beetles and other natural enemies of whiteflies and other pests.
Grow flowering insectary plants to provide nectar and pollen to nourish adult natural enemies.
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 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

At least 191 species of lady beetles occur in California. These include at least 3 Delphastus species: D. catalinae, D. dejavu, and D. sonoricus. Whether D. pusillus occurs in California is uncertain. For many years D. pusillus was thought to be the common whitefly predator throughout California. However, a revision of the genus and reexamination of museum specimens revealed the common California species is actually D. catalinae. Delphastus pusillus and other Delphastus species occur in the Eastern United States.