Franklinothrips Predatory Thrips / Home and Landscape / UC Statewide IPM Program (UC IPM)

Hosts or Prey

Thrips, spider mites, whiteflies, and various other small arthropods

Identification

Franklinothrips females are fast-running insects that in the field are easily mistaken for ants or adults of Bethylidae wasps. Franklinothrips species are commonly called ant-mimicking predators due both to their appearance and behavior.

Adult female Franklinothrips have a somewhat narrow, wasplike waist. The antennae, body, and legs are mostly dark brown or black. There is yellow or whitish on abdominal segments two and three and a portion of the legs.

Male F. vespiformis do not occur in some populations or are rare. Franklinothrips orizabensis has both females and males. In comparison with females, F. orizabensis males are smaller, less antlike in appearance, and have longer antennae. Males have a less constricted waist, darker antennae, and paler wings.

Adults, mature larvae, and pupae are 1/10 to 1/8 inch (2.5–3 mm) long. The eggs occur hidden inserted in plant tissue. Eggs are kidney-shaped (oblong with an indentation), translucent white, and about 1/40 inch (0.6 mm) long.

First instars initially are entirely pale yellow or whitish. As they age the larvae develop a bright red, bulbous abdomen. With the naked eye in the field, older larvae resemble a moving red dot. Viewed from the side, older larvae appear hunchbacked where an orangish, swollen area occurs on a portion of the thorax.

The mature larva (prepupa) produces an oval, semitransparent, silken cocoon in which it pupates. Cocoons occur on the underside of leaves, on plant parts near the ground, and sometimes in litter beneath plants.

Lookalikes

Franklinothrips orizabensis and F. vespiformis cannot be distinguished in the field. However, properly prepared specimens examined under magnification can be distinguished to species. Female F. vespiformis have rounded tips on their slender forewings and a pale area near the forewing tips. Female F. orizabensis lack the pale area near the forewing tip; the forewing tips are brown and more broad in comparison with those of F. vespiformis.

Life Cycle

Franklinothrips hatch from an egg and develop through four immature stages, two each larval (nymphal) and pupal stages before maturing into adults. The first stage pupa is called a prepupa or propupa.

Adult females use their curved ovipositor to insert eggs singly into plant tissue with only the egg tip protruding. The female sometimes deposits a yellowish substance on the eggs' protruding tip. In F. orizabensis males are produced from unfertilized eggs and females arise from fertilized eggs. During her lifespan of about 1 month an adult female can lay about 150 to 200 eggs.

Both adults and larvae are predaceous on small arthropods. When feeding the thrips grasp prey with their front legs, lift it into the air, and consume the arthropod.

Egg to adult development time is about 3 weeks when temperatures are warm. Franklinothrips have several generations per year and can be active throughout the year where winters are mild.

Habitat

These Franklinothrips are native to tropical areas in Central and South America. They have been deliberately introduced for biological pest control or inadvertently spread to locations including Australia and Europe.

Franklinothrips vespiformis is generally found on low-growing plants, such as various ornamentals and in vegetable crops and gardens including on beans, chilies, eggplant, and melons. Franklinothrips orizabensis occurs mostly on trees and shrubs. It is an important natural enemy of avocado thrips and greenhouse thrips in southern California avocado groves.

Species

At least 14 Franklinothrips species are known. Of these only Franklinothrips vespiformis and F. orizabensis are reported in California. Franklinothrips vespiformis is officially named vespiform thrips. Franklinothrips orizabensis has no official common name.