More Pesky Insects in the Garden and Landscape

Aphids: A small, prolific problem

Aphids are one of our smaller insects, only 1/16th to 1/8th inch in size. Aphids are pear-shaped, round, oval, spindle or elongate in shape. They can be black, grey, red, orange, yellow, green, brown, blue-green, pink or other colors. Some aphids feed on foliage while others feed on twigs, limbs, branches, fruits, flowers or roots of plants.

Aphids damage plants by: (1) causing plant stress by directly removing plant juices; (2) reducing the quality of the plant by secreting excess plant sap as honeydew which then grows a black-colored fungus called sooty mold; (3) honeydew discolors the foliage preventing sunlight from reaching the plant for photosynthesis; and (4) possibly transmitting plant diseases. Aphids are very prolific insects.

The cotton, or melon, aphid can develop into an adult in 4 to 10 days and each one can produce about 85 young during their 3 to 4 week lifespan. This aphid is yellow to dark green in color and feeds on a wide variety of plants including asparagus, beans, begonias, catalpa, clover, cucumbers, ground ivy, hydrangeas, okra, spinach, strawberries, tomatoes, and even weeds.

The woolly aphid is not itself wooly, but produces large quantities of woolly wax filaments on leaves of trees such as apple, ash, elm, and oak. These aphids are reddish-purplish, wingless or winged, and covered with woolly, bluish-white wax masses. There are several species of aphids that feed on pecan trees. These adults are clear to yellow or pale green. The nymph stage appears solid yellow. Heavily infested trees can accumulate honeydew on leaf surfaces and cause premature leaf drop.

A green peach aphid can be pink as well as green and has three darker stripes down its back. This aphid produces live young at the rate of 3 to 6 per day for several weeks. There may be as many as 30 generations a year of this aphid. It dines on lettuce, peaches, potatoes, spinach, tomatoes, and a number of ornamental flowers, including chrysanthemums.

Most aphid populations are moderated by natural controls that include environmental stresses (high winds, heavy rains, extreme temperatures, etc.) and natural enemies (lady beetles, green lacewings, syrphid fly larvae, damsel bugs, some wasps and parasitic fungi. Chemical control of certain aphid species has become extremely difficult due to resistance to insecticides. Insecticides and cause aphid populations to dramatically increase following application, a result of the destruction of natural enemies and failure to control the aphid itself.

If you have an infestation problem, contact the AgriLife Extension office for the latest information on control for the species you have.

Sycamore Lace Bug

This adult insect is whitish in color and about 1/8th to 1/4th inch long with highly ornamented wings and a hood-like structure covering its head. The entire surface is covered with veins that resemble lace. The immature nymphs are similar in appearance, but smaller and often with spines. Both nymphs and adults have piercing/sucking mouth parts. Nymphs hatch from eggs in a few days and develop through 5 stages before becoming adults. This development occurs in about 30 days depending on temperature and other environmental conditions. Three to five generations can be produced annually.

All life stages occur together on the undersurface of leaves on sycamore, ash, cedar elm and hickory. The upper surface of infested foliage becomes marked with white to yellowish and later brown speckles. The undersides of infested leaves become marked with black varnish-like spots and old skins of previous nymphs often remain attached to the leaves.

A severe infestation may cause defoliation in late summer. Damage is more severe during dry weather. Established trees can handle low to moderate infestations, but several years of heavy infestations along with other stresses can kill a tree. Newly planted or young trees don’t tolerate damage well.

The lace bug has many natural enemies including the assassin bug, minute pirate bug, lacewing, spiders and predaceous mites. A strong stream of water from a hose will dislodge young nymphs as they hatch, controlling small populations.

Chemical control is more effective before infestation becomes severe.

There are several other lace bug species in Texas that can become abundant on particular host plants: oak lace bug, hawthorn lace bug (also on quince and pyracantha), cotton lace bug and lantana lace bug (also on Texas sage).

If you have an infestation problem, contact the AgriLife Extension office for the latest information on control for the species you have.

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.