Thrips are small insects that can cause big problems in the landscape. They attack a wide variety of ornamental plants and their numbers can increase rapidly if left unchecked. Although they may be present throughout the growing season, highest populations are in the spring.
These pests are slender and from 1/16 to 1/8 inch long. Adults may be yellow, brown or black.
They damage plants by sucking out the juices from the leaves, flowers, or fruit.
Indications of a thrips infestation include leaves that appear bleached, stippled or silver or that wilt, dry up, and drop prematurely. Brown specks of excrement are deposited on the undersides. Red-banded thrips – who love mango and avocado -produce a lot of honeydew, and Cuban-laurel thrips produce curling leaves with purple spots.
Buds may fail to open, or flowers may be deformed, streaked, or discolored.
To look for thrips in your garden, shake the foliage over a sheet of white paper and look at the fallout with a magnifying glass. You can also use a sticky trap to monitor them. See the websites listed below for descriptions and photographs of various thrips species.
Thrips can go through their entire life cycle in 11 to 21 days. Eggs are deposited in leaf tissue, and the insects go through four other stages before adulthood. Nymphs are very active.
A variety of beneficial insects such as lacewings and lady beetles help to keep thrips populations in check but pesticides, including insecticidal soaps, are also effective.
See the following publications for further guidance.