Friday, July 31, 2009

August is the Time for Cicada Killers

Cicada killers are most active during late July and August, which coincides with the appearance of cicadas. Cicadas are large insects that “sing” in the trees during late summer. The female cicada killer will search tree trunks and lower limbs for cicadas, which she will sting and drag back into her burrow.
The female cicada killers usually dig burrows in areas that are sandy, bare, and exposed to full sunlight. They prefer to nest in areas of little vegetation, compared to thick areas of turf grass. Each female captures at least one cicada (some collect two or three) and a single egg is laid in the cicada before being sealed off. Even though an area may contain many burrows, female cicada killers are solitary wasps. This means that each female constructs a burrow and captures her own cicadas to serve as food for her developing young. The cicada killer develop through complete metamorphosis, with four life stages: egg, larva, pupae and adult. However, there is only one generation a year.
Adult cicada killers feed on flower nectar and sap. The female wasps are non-aggressive and rarely sting unless disturbed. Male cicada killers are usually aggressive and tend to defend nesting sites. However males lack a stinger, so they are harmless.

Some Control Options:
Non-Chemical Control Options:
1) Apply fertilizers and water turf grass to promote growth.
2) Also place mulch in flowerbeds and around shrubs to cover sandy soil to help reduce cicada populations.

Chemical Control Options:
Control is usually not recommended, since this is considered a beneficial insect. However these wasps can become a problem in high traffic areas around homes and in commercial areas such as around swimming pools, flower beds, and golf course greens.
If control is necessary, first the nesting sites should be located. One treatment option is to sprinkle 1 tablespoon of carbaryl dust into the burrow and then close the entrance of the burrow. Other suggestions for spray treatments that are labeled for wasp control include acephate, allethrin, cyfluthrin, cypermethrin, permethrin, and resmethrin. Treatments may be needed for two to three weeks as new wasps move into the area.

Cicada killer, Sphecius speciosus (Hymenoptera: Sphecidae). Photo by Bart Drees, Professor and Extension Entomologist, Texas A&M University.

Monday, July 20, 2009

Warm, Dry Weather Means Chinch Bugs

The southern chinch bug, Blissus insularis, can be one of the most damaging insects to St. Augustine grass in Texas. Even though St. Augustine grass is the primary host of the southern chinch bug, they can also attack bermudagrass, bahiagrass and zoysiagrass. Both nymphs and adults remove sap from the base of plants and inject a toxic substance that prevents transportation of water within the plant. Damage appears as irregular patches of dead or stunted grass surrounded by a halo of yellowing, dying grass. Damage increases during hot, dry weather.
Chinch bugs develop through incomplete metamorphosis with an egg, nymph and adult stage. The nymphal stage appears orange-red in color with a pale white band across the third part of their bodies, the abdomen. As they molt, the nymphs will change in color from orange-red to black and develop wings. The adult chinch bugs have black bodies with fully developed white wings that contain black triangular markings on the outer margins. The entire life cycle from egg to adult can occur in about 7 to 8 weeks, so more than one generation can occur in a year.
One way to detect chinch bug infestations is to use an open-ended can immersed in the soil filled with water. The water causes the chinch bugs to float to the top of the can. The can should be placed in different locations within the damaged grass, totaling a square foot sample area. If 20 to 25 chinch bugs are found within a square foot of sampling, then control is needed.

Some Control Suggestions:
Non-Chemical Control Options:

1) Keeping thatch to a minimum, by aerating the lawn or top-dressing, will reduce chinch bug populations.
2) Too little or too much water also can cause chinch bug problems. Over-watering results in saturated, oxygen-deprived soils which contain few microbes needed to decompose thatch. Dry lawns should be watered immediately when edges of grass blades begin to curl or if the grass does not spring back quickly when stepped on.
3) Keep beneficial insects in the lawn such as big-eyed bugs (Geocoris spp.) and minute pirate bugs (Xylocoris spp.), since these are predators of chinch bugs.

Chemical Control Options:
A variety of liquid and granular insecticides are available to control chinch bugs. Granular insecticides can be applied with a standard fertilizer spreader and should be watered in with 1/4 inch of water to activate the insecticide. Liquid insecticides are usually applied using a hose-end sprayer.
If chinch bugs are in an isolated area of the lawn, spot treatments can be used. The off-colored turf and all surrounding infested areas should be treated. Spot treatments can minimize the impact of insecticides on beneficials and help avoid environmental contamination.
Products containing such chemicals as acephate, imidacloprid, lambda-cyhalothrin, bifenthrin and permethrin can be used to control chinch bugs.

Photo: Chinch bugs, Blissus spp. (Hemiptera: Lygaeidae), nymphs and adults. Photo by Bart Drees, Professor and Extension Entomologist, Texas A&M University.

Sunday, July 12, 2009

Abundance of House Flies

As we venture in and out of buildings be might have a piggy-backer, the house fly (Musca domestica) joining us indoors. This fly is not only a big nuisance insect, but it can sometimes carry other organisms that can cause diseases in humans and domestic animals. This makes suppressing house fly populations very important.
House flies are ¼-inches in length, light grey in color and have four longitudinal black stripes on their thorax. They also have a pair of large, red-brown compound eyes and sponging mouthparts, so they are non-biting flies.
Adult house flies live up to three weeks and are active during warmer weather. The adult female flies deposit eggs in clusters of 50 to 100 within a variety of moist, decomposing organic substrates including animal manure, accumulated grass clippings, garbage, spilled food and animal feed. The eggs usually hatch into larvae within 12 hours. The larvae then feed on the decomposing organic material as they continue to grow in size. Then the larvae will stop feeding and migrate to drier substrates to pupate. Adult flies will emerge within three days to four weeks, depending on the temperature.

Some Suggestions for Control:

Non-Chemical Control Options:

Frequently clean surfaces and properly dispose of food and other organic materials within a sealed garbage bag. Garbage containers should be closed and placed away from doors to prevent fly breeding and entering buildings. The garbage container should be cleaned a couple of times a month with soap and water to decrease amount of accumulated organic matter. Make sure that windows screens and screen doors do not have holes in order to minimize house fly access. Retail buildings can install air curtains above exterior doors to make it harder for flies to enter. Several types of traps are available that do not contain toxic chemicals, such as sticky traps and ultra-violet light traps. All traps need to be placed at least 5 feet away from food processing areas to avoid contamination. Sticky traps need to be replaced frequently as they loose their effectiveness with time. In addition, a fly swatter can be used to kill the occasional invader!

Some Chemical Control Options:

Chemical control should not be the only control option used, since the overuse of insecticides may lead to secondary problems such as insecticide resistance and increased allergies and other health problems. Some house fly insecticides are sold as aerosol sprays or bait formulations and can be applied to such areas as dumpsters. Several insecticidal sprays labeled for house fly control in and around buildings contain permethrin, tetramethrin or resmethrin. Fly baits are usually sugar-based and contain a compound that attracts the adult flies. The flies that feed on these baits are then killed after injesting the insecticide.

Photo of house flies, Musca domestica Linnaeus (Diptera: Muscidae), mating. Photo by Dr. Bart Drees, Professor and Extension Entomologist.