Inspect for Arthropods

Arthropod pests, including insects and spider mites, produce characteristic damage related to the way they feed, determined by their type of mouthpart: chewing, rasping or sucking.  The damage is usually easier to detect than the pests themselves.

Identify the pest before using a pesticide.  Many of the small insect and mites you see are beneficials and will be preying on the harmful insects.  Do a visual inspection of random leaves, particularly of underside of leaves where pests hide.  The effort invested in making correct pest identifications can save you money by eliminating unnecessary pesticide applications.

Chewing Insects

Caterpillars (immature stages of moths and butterflies) like tent caterpillars, sawflies, grasshoppers, and beetle larvae  have chewing mouthparts that remove plant tissue.  They chew holes in leaves, skeletonize leaves or defoliate plants. They may also tunnel in petioles and stems or consume them entirely. Recently damaged plants will have freshly damaged edges. Later the edges turn brown and die. Sometimes silk is found at some caterpillar feeding sites, or fecal material (excrement) in the vicinity of the damage.  Beetles and grasshoppers often leave after feeding but caterpillars may finish feeding and pupate before they are detected.

Leafminer flies, the immature stages or maggots of small flies, produce blister-like trails or blotches in leaves. The 1/8-inch yellow maggots have chewing mouthparts which tease apart the tissue between the outer layers of leaves. They feed inside leaves for several days before emerging to pupate on the ground.  This stage lasts about 2 weeks. Adults look like tiny house flies (less that 1/8 inch long) marked with yellow and black patterns.  Female flies damage plants during egg laying by producing small, circular indentations, called stipples, on upper leaf surfaces.

Rasping Insects

Thrips are tiny (1/32 to 1/16-inch long), slender insects. Adults have hairy wings; immature thrips do not. With their sword-like mouthparts, thrips feed by slicing or rasping open plant cells on the surfaces of leaves, buds, flowers or fruits and sucking the contents out of the ruptured cells.  On mature plant parts, their feeding causes tiny silver streaks which are rows of empty, dead cells. If plant parts are still growing when attacked by thrips, the damaged surface cells stop growing and undamaged cells continue to develop around them. This causes deformed plant parts. Occasionally, thrips are no longer present when these deformities begin to show.  Thrips will also feed on pollen, and some thrips species prey on other insect and mite pests. Thrips migrate into landscape areas when nearby weeds and wildflowers begin to mature and die.

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.  For help in identifying insects pests contact contact the AgriLife Extension office. The Texas AgriLife Extension Service, Fannin County office is located in the South Annex, 210 S. Main, Bonham.  Phone – (903)583-7453. E-mail: fannin-tx@tamu.edu