Plants Attacked

The adults feed on a wide variety of evergreen, deciduous, and herbaceous plants. The larval form is destructive on yew (taxus), hemlock, rhododendron, and several other broad-leaved evergreens. Adults and larvae will sometimes feed on strawberry and impatiens.

Description of Damage

Two kinds of damage are conspicuous: Adults chew marginal notches in leaves, causing damage that quite often is confused with a disease or chemical injury. The adults feed from the outer margin of the leaf inward, creating characteristic notches, and these notches can be used as an early indicator of potential larvae in the soil. Adults cut notches on the margins only; they never create holes on the center of the leaf.

Adult thrips are small, pale-yellow insects (occasionally black) with elongated bodies, and fringed wings.

Life Cycle

Their life cycle consists of an egg, nymph, pre-pupa, pupa and an adult. The exact time required for thrips to complete their life cycle varies with species, temperature and the host plant. Western flower thrips complete their life cycle, from egg to adult, in approximately 10 days at 80° F. Adults insert eggs in leaf tissue which hatch in approximately three days. Nymphs feed for four to five days and then drop from the plant to pupate in the soil. Adults emerge after two days of pupation and begin feeding.

Whiteflies are white insects with pale yellow bodies that are approximately 2 mm long. They belong to the order Homoptera and are close relatives of aphids, scales, mealybugs, hoppers and cicadas.

Life Cycle

The life cycle consists of an egg, 4 nymphal instars, a pupal and an adult stage. Depending on the species and environmental conditions, eggs require 10-12 days to hatch, and completion of life cycle from egg to adult takes 30-40 days. Nymphal instars behave in a manner similar to scale insects. The first nymphal instars are active and they are sometimes called crawlers. The remaining nymphal instars are sedentary and may mimic immature scales.