Sucking insects feed by puncturing plant parts with their long, straw-like mouthparts and removing sap, causing plant stress and sometimes making plants appear wilted.  Sucking insects also cause plant deformities similar to thrips damage on growing plant parts. Some mealybug species feed below the soil on roots.  Aphids, whiteflies, mealybugs and scales (all usually less that 1/8-inch long), as well as the larger plant bugs and stink bugs, are sucking insects.

Aphids can be identified by the two “exhaust pipes,” called cornicles, on the ends of their abdomens, and they may or may not have wings.

Whitefly immatures look like scale insects on the undersurfaces of leaves, but adults can fly when disturbed.

Mealybugs are covered with white, waxy ornamentations and crawl along the surface.

Scale insects attack leaves and stems, and look like variously shaped domes attached to the plant.

Chinch bugs in turfgrass inject toxic salivary secretions into plant tissues as they feed, which causes extensive yellowish or reddish areas or dead areas. Damaged or dead leaf spots sometimes fall off the plant, leaving holes that might be mistaken for chewing insect damage.

Aphids, whiteflies, mealybugs and scale insects remove more sugar-rich fluids from plants than they need and eliminate this sticky material, called honeydew, around feeding sites. A fungus called sooty mold grows on leaves covered with honeydew.  This black mold decreases the aesthetic value of plants and stresses them further by blocking the sunlight needed for photosynthesis. Some sucking insects can transmit plant diseases.

Non-insect Arthropods

Spider mites, the tiny (1/32-inch long) eight-legged relatives of insects, produce damage similar to that of thrips. However, they use their mouthparts to first pierce plant cells and then to suck out the contents. Spider mite damage gives a stippled appearance to leaf surfaces, causing leaves to appear bronzed. Infestations always begin on the underside of leaves. Breeding infestations can be identified by the whitish cast skins of developing mites. Mites also produce silken webbing around infested plant parts. Outbreaks often occur during drought stress or after the use of broad spectrum insecticides that allow mites to survive while eliminating their natural enemies. Repeated applications of miticides should be made after spider mites are first detected, since the egg stage is usually unaffected.

If the cause of a plant health problem is undiagnosed, control measures are often futile. Plant deformities or irregular growth may be caused by insect pests that have already left or ones that are difficult to identify, as well as by disease, improper watering or fertilizing, toxic compounds and other problems.

For help in identifying insects pests contact the Texas AgriLife Extension Service office at 903-583-7453.

Extension entomology  programs provide identifications, fact sheets and publications. An identification form is available to submit insect and mite samples.  Texas Plant Disease Diagnostic Lab provides plant disease diagnostic support to Texas AgriLife Extension Service and the general public.   

A Field Guide to Common Texas Insects (Bastiaan M. Drees and John A. Jackman (1998)) has many pictures of common insects.  The guide is also available online.