Friday, March 27, 2009

Time to treat for fire ants!

Red imported fire ants, Solenopsis invicta Buren, are an invasive species that has infested over 300 million acres in the southern United States. On average, Americans spend over $6 billion a year on medical bills, repairing damage to electrical wiring and purchasing insecticides for treatment of fire ants. For these reasons, the use of chemicals is needed to manage their populations, in order to allow the native ant species back into the landscape.
Fire ant baits, drenches, dusts and contact insecticides may be applied to control fire ants. It is advised to treat the individual fire ant mounds directly if less than 5 mounds are found within a 1/4 acre or less than 20 mounds within 1 acre, since this is not considered an infestation. However, if more than 5 mounds are present within a 1/4 acre or 20 mounds within an acre, then a fire ant bait or contact insecticide should be broadcasted over the entire infested area. Fire ant baits are made up of defatted corn grit covered with insecticide and soybean oil. The delivery process of baits into the colony is so effective, that the amount of insecticide applied within an area is significantly reduced. Before broadcasting the fire ant bait, foraging activity should be assessed, by placing a potato chip or hot dog next to the mound. If fire ants find the chip or hot dog within twenty minutes, then it is a suitable time to broadcast the bait. Fire ants will typically actively forage when the soil surface temperature is between 70 and 90° F, which is between May and September. Fire ant baits should never be watered into the soil and they should not be applied if they smell rancid. On the other hand, contact insecticides can also be broadcasted over the entire infested area and need to be watered into the soil. Control using contact insecticides generally lasts for 6 to 12 months, depending on the active ingredient within the insecticide.
Both fire ant baits and contact insecticides can be broadcasted using a hand-held spreader for small areas or a Herd Seeder can be mounted onto a truck or ATV for larger areas.
For more information, please visit the fire ant webpage at

Photo of fire ant workers. Photo by Bart Drees, Professor and Extension Entomologist, Texas A&M University.

Friday, March 13, 2009

Mining the Leaf

Moving plants indoors during the winter allows for excellent breeding conditions for many insects. One of these flying insects a leafminer agromyzid fly in the genus Liriomyza. Liriomyza leafminers can be found on numerous outdoor plants, including chrysanthemums, asters, zinnias, marigolds, daisies, eggplant, carrot, potato, garden peas, lettuce, tomato, cucumber, and pepper plants.
Adult leafminers are 1/16 inches in length with grayish-black bodies and yellow markings. The female flies insert their eggs into the leaves. The eggs hatch usually in 2 days into 1/16 inch larvae. These whitish-yellow larvae cause plant damage, by tunneling through the leaf tissue. As the larvae mature, the tunnel or mine gets larger in size. After 7 or 8 days, the last larval stage emerges from the leaf to pupate in the soil. The adult fly will emerge usually in 7 to 11 days. The lifecycle from egg to adult may last all year, if the leafminer is in a controlled environment.
The white tunnel that appears on the leaf is both unappealing to the eye and can cause leaf drop in some instances. Leaf mines reduce the value of the crop and they can reduce the photosynthetic ability of the plant. If large populations exist, they have the potential to retard growth of young plants and lower fruit yield.

Some Control Options

Some Cultural Control Options:

1) Prune off and dispose of infested leaves and branches.
2) Properly irrigate and fertilize plants to ensure healthy plants.
3) Plant cultivars that are more tolerant to leafminer attack.
4) Cover the soil with plastic to prevent larvae from pupating.

Some Chemical Control Options:

Organics sprays such as horticultural oil, neem and spinosad can be used to control leafminers. Also systemic insecticides such as acephate and imidacloprid can be used to control leafminers.

Photo of leafminer adult, Liriomyza sp. Photo by: Texas AgriLife Extension, Department of Entomology, Texas A&M University.

Tuesday, March 3, 2009

Attack of the Aphids

Aphids are small, soft-bodied winged or wingless insects about 1/25 to 1/8 inches in length, with relatively long legs and antennae. Aphids can vary in color from black, green, yellow to even pink. Some aphids lay eggs, while others give birth to live young that can mature in as little as 7 to 8 days. Aphids have piercing-sucking mouthparts that remove phloem from the plant, causing distortions in young leaves and stunting new growth. They can also feed on flower buds, which cause deformities.
Since aphids feed on phloem they excrete honeydew, which is a shiny, sticky waste product that collects onto lower lying leaves. Once deposited, the honeydew is a nice food source for sooty mold which will begin to grow on the underlying foliage. Sooty mold will inhibit photosynthesis, so its growth can potentially cause severe harm to the plants.

Some Control Options

Some Non-Chemical Control Options: Conserve beneficial insects, such as spiders, praying mantids, assassin bugs, lacewings, ladybird beetle larvae and adults and parasitic wasps in outdoor landscapes. Also spraying water streams is effective to dislodge aphids from plants.
Some Chemical Control Options: Insecticidal soaps and oils can be used to control aphids and are considered low impact insecticides. Other foliar insecticides containing such active ingredients as permethrin, cyfluthrin, carbaryl, deltamethrin, pyrethrins and tebufenozide or systemic insecticides such as those containing imidacloprid or acephate can also be used.

Photo of crape myrtle aphids, Tinocallis kahawaluokalani (Kirkaldy) (Homoptera: Aphididae. Photo by Bart Drees, Professor and Extension Entomologist, Texas A&M University.