Adult -The small (1.25-mm), winged flower thrips is yellowish brown to amber with an orange thorax. The male is slightly smaller and lighter in color than the female.
Egg -The flower thrips' delicate egg is cylindrical and slightly kidney shaped with a smooth, pale or yellow surface.
Larva -The tiny young thrips is lemon yellow, resembling the adult except for its lack of wings.
Host Plants -Flower thrips have been collected from 29 plant orders, including various berries, cotton, day lilies, field crops, forage crops, grass flowers, legumes, peonies, privet hedges, roses, trees, truck crops, vines, and weeds. They seem to prefer grasses and yellow or light-colored blossoms. Roses are most susceptible in June.
Damage -Flower thrips are one of the most numerous insect pests of ornamental crops. In warm periods, this species often flies in late afternoon in swarms of tiny, orange insects. "When they light, they bite," as the old saying goes; and thrips do bite people, causing a noticeable stinging sensation. Their large numbers account for considerable and rapid damage to flowers, especially those with light-colored petals. Yet thrips contribute to pollination, an unexpected benefit!
Life History -Flower thrips are generally found at the base of the flower's petals. They reproduce throughout the year in North Carolina, with the majority of their 12 to 15 generations occurring during the warmer months. Newly emerged females begin to lay eggs within 1 to 4 days in summer and within 10 to 35 days in winter, reproduction being much faster in warmer weather. In summer the adult stage is reached in about 11 days. Flower thrips pass through egg, two larval, prepupal, pupal, and adult stages. The eggs are inserted into flower or leaf tissue, and the prepupal and pupal stages are spent in the soil. In summer flower thrips may live 26 days, though overwintering thrips may live all winter. Flower thrips can overwinter as far north as North Dakota in grass clumps and other sheltered refuges.
Flower thrips are consumed by green lacewings, lady beetles, insidious plant bugs, and salamanders; yet control of thrips is difficult because of their constant migration from weeds, grass, flowers, and trees. The destruction of old rose blossoms and the application of pesticides at close intervals can help reduce damage. For specific chemical controls, see the current state extension service recommendations.
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