Western flower thrips

The western flower thrips is an important pest insect in agriculture. It has been documented to feed on over 500 different species of host plants, including a large number of fruit, vegetable, and ornamental crops. The adult male is about 1 mm long; the female is slightly larger, about 1.4 mm in length. Most western flower thrips are female and reproduce by arrhenotokous parthenogenesis; i.e. females can produce males from unfertilized eggs, but females arise only from fertilized eggs. Males are rare, and are always pale yellow, while females vary in color, often by season, from red to yellow to dark brown. Each adult is elongated and thin, with two pairs of long wings. The eggs are oval or kidney-shaped, white, and about 0.2 mm long. The nymph is yellowish in color with red eyes.

The lifecycle of the western flower thrips varies in length due to temperature, with the adult living from two to five or more weeks, and the nymph stage lasting from five to 20 days. Each female may lay 40 to over 100 eggs in the tissues of the plant, often in the flower, but also in the fruit or foliage. The newly hatched nymph feeds on the plant for two of its instars, then falls off the plant to complete its other two instar stages. The insect damages the plant in several ways. The major damage is caused by the adult ovipositing in the plant tissue. The plant is also injured by feeding, which leaves holes and areas of silvery discoloration when the plant reacts to the insect's saliva. Nymphs feed heavily on new fruit just beginning to develop from the flower.