During warm weather, thrips often fly in swarms in late afternoon. Thrips seem to prefer light-colored blossoms. They feed on petals and buds by rasping soft plant tissue and sucking the juices. 

Thrips breed primarily on grasses, weeds, and clover. Flowers are infested from thrips that come from these sources. Female thrips insert eggs into plant tissue. These eggs hatch into larvae that feed in the same manner as the adults. 

When the larval stage is complete,, non-feeding prepual and pupal stages are spent either on the plant or in the soil. Emerging adults return to the plant to feed. Thrips' life cycle may be completed in 10 to 12 days in the summer or a month or more in cool weather. Thrips may reproduce year-round in South Alabama. There are several generations a year. 

The western flower thrips has recently become a problem on ornamentals. This thrips is especially difficult to control. 

Description

Adult flower thrips are tiny, black to straw-colored insects approximately 1 millimeter long. Males are slightly smaller than females. Adults have fringed wings with close-set long hairs. 

Thrips prepupae and pupae are inactive and have developing wing pads. Larvae are pale yellow and resemble adults, but they are smaller and lack wings. Eggs are smooth, kidney-shaped, and light-colored. 

Damage

Flower thrips feed by rasping soft plant tissue and sucking the juices. Petals become blotched or streaked with discolored areas. Buds are distorted and do not open properly. 

Host Plants

Thrips injure too many plants to list here. Among the most favored plants are roses, peonies, daisies, gladiolus, chrysanthemums, cotton blossoms, legume blossoms, grass blossoms, day lilies, and truck crops. 

Control

Control is difficult because plants are continually infested by migrating thrips. Here are a few thrips tips for the homeowner.

• Collect and destroy all old blossoms and damaged buds from roses and bedding plants.
• Keep borders and plant beds weed-free. Control weeds outside small greenhouses. A 4- to 6- foot weed-free border outside may slow down the movement of thrips into the greenhouse. 
• Maintain plants properly. Although watering keeps plants green, drought-stressed plants do not withstand other stresses-such as thrips feeding-as well.

The pesticide rates in this publication are recommended only if they are registered with the Environmental Protection Agency and the Alabama Department of Agriculture and Industries. If a registration is changed or cancelled, the rate listed here is no longer recommended. Before you apply any pesticide, check with your county Extension agent for the latest information.

Trade names are used only to give specific information. The Alabama Cooperative Extension System does not endorse or guarantee any product and does not recommend one product instead of another that might be similar.

For more information, contact your county Extension office. Look in your telephone directory under your county's name to find the number.