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.
Plant injury is caused by both nymphs and adults rasping the bud, flower and leaf tissues of the host plants, and then sucking the exuding sap. This causes distorted and discolored flowers or buds and gray or silvery, speckled areas on the leaves.
Tomato spotted wilt virus, a tospovirus, is found throughout the world and has a very wide host range infecting plants in over 50 families. In peanuts, TSWV is transmitted by thrips. The virus, acquired only by larvae, may be transmitted by larval and adult thrips. Yield losses attributed to TSW have been reported to exceed 50% in fields with high disease incidence.
Symptoms of TSW are variable. Plants infected early in the season may be stunted, mottled and distorted (third image). A common symptom is the presence of light green to yellow rings on leaflets (fourth image).
Thrips reproduce throughout the year 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.
Thrips are very small (1.25-mm or less), fringe winged, and yellowish brown to amber with an orange thorax. The male is slightly smaller and lighter in color than the female.
Please contact your local county extension office for current information.