Here are the bugs of August. Some are a little unusual, especially the parasite.
1. Ensign wasps — Evaniidae — These little wasps are black, black-and-red or bright, shiny, dark blue that appear deformed on first glance. The abdomen is attached to the thorax very high above the hind coxa, and the abdomen appears to be a flag at the end of a long thin pedicle. It is somewhat triangular in appearance. These are beneficial parasites of the egg cases of cockroaches. They can be found in large storage warehouses and in woody areas. They are attracted to high populations of cockroaches. Although a wasp, it does not sting and when found should be released to complete its designed task reducing the cockroach populations. We have several reports of them around the state -- some indoors and others on trees. This may be a result of the weather conditions concentrating roaches in certain areas or locations. Figure1.
2. Armyworms — This population is not a stranger, as each year about this time we see increasing numbers in the grass in yards, pastures and open fields. A prime indicator of these populations is the flocks of birds seen gathering in areas of infestations. Sometimes webbing can be seen over the lawn or pasture where these infestations are beginning. For the homeowner or cattle farmer or hay producer, these pests need to be managed to keep the grass or the hay for baling. On occasion armyworms have been known to infest bales of hay and eat enough for the bale so it falls apart. Management in pastures can be made with Sevin, Confirm, Tracer, Intrepid, Lannate or methyl parathion and in home lawns with Acelepryn, Arena, Battle, Mach 2, Conserve, Spinosad, Sevin, Deltic and Maverick Aquaflow. In sugarcane fields, the armyworm is an excellent herbicide, eating grasses competing with the newly planted cane. Occasionally they get on sugarcane but do not cause any loss – they only make the cane look ragged and damaged. These armyworms on sugarcane are heavily parasitized by a braconid wasp and a tachinid fly. At maturity the larvae of the braconid wasp leave the host and spin a silken web-like mass on the foliage of the sugarcane, and inside this mass the larvae pupate. A few days later they emerge and go about looking for other armyworms or alternate host to begin the cycle again. The tachinid flies lay their eggs on the host, and the small white eggs can be observed on the back of larvae near the head. The hatching larvae bore into the host and develop internally. At maturity the larva leaves the host and pupates nearby. If they are sprayed, the farmers would lose these valuable, little parasites. Figure 2 and 3.
3. Red-headed azalea caterpillars — These voracious caterpillars are out now and will be out probably through September. Presently they are out just a little earlier than usual and are defoliating azaleas. At hatch the caterpillars are magenta in color with long gray hairs. Later have yellowish white stripes with a red head, belly and tail. At maturity they are black, with broken white lines down the dorsal part of the body and a red head, tail and belly. These caterpillars eat constantly and will strip young plants almost overnight. Management of these pests is best with Orthene, Spinosad or a pyrethroid. Be sure to add a little surfactant like soap to assure the material sticks to the body of the caterpillar. Make sure the pH is applicable to the spray, otherwise you will be repeating the application shortly. Best pH is between 5.5 and 6.5. Water pH can be adjusted with a buffer and measured with a digital pH pen. Be sure to adjust the pH before the insecticide is added to the solution. Figure 4.
4. Lantana lace bug — This lace bug is one that infests deciduous plants. This means that it overwinters as an adult in the leaf litter under and around the base of the plant. Good management strategy is to clean up under and around the plant during winter to help the environment mange some of the pest population. Like their counterparts, they have a piercing, sucking mouthpart. Eggs are deposited on the stems and foliage in the spring as the plants begin to grow. The hatching nymphs resemble the nymphs of other species except for color. Their feeding causes the leaf tissue to become stippled and discolored, and with heavy feeding eventually turns a bronzy gray color. Heavy damage can cause early defoliation and reduced bloom. Management can be completed with Merit, cyfluthrin or other pyrethroid or Orthene. Figure 5.
5. Asian hackberry aphid — Once again it’s “snowing” in some parts of Louisiana. Hackberry trees are turning black, and the leaves are full of aphids. What makes them bad are the vast numbers, the heavy honeydew excretion and the large wax secretions on the body that make them look like snowflakes when they fall off the leaves and float or fly through the air. These aphids are not a problem on other plants. Management is easy through the use of a systemic like Cygon, Merit or Orthene. The ground, furniture, plants or vehicles under the hackberry trees are usually covered in sooty mold because of the heavy honeydew excretions. Figure 6.
6. Rose borer — A little cerambycid larva was collected from Knock Out rose stems. The larva appears to be in the genus Obera. I was unable to key the larva, but it hollows out the stems just like the dogwood twig borer. Every so often the larva cuts a hole along the stem to remove frass and chewed wood. The larva moves very quickly in the hollowed-out stems. First signs of infestation are the dying back of the infested branches. Although hollowed-out, the stems remain green a long time before dying back. Some hollowed stems were 8 inches long, and only the tips were showing signs of injury. Upon inspection, the small holes can be noted along the stems. (Figure 7.) The adults should be a small, elongate beetle about 1 inch or less feeding on the pollen in the flowers. In order to identify the beetle causing the problem, I will need to see some of the beetles. Any little, elongate beetles observed in the rose blossoms should be collected and sent in for identification. This may be only an isolated incident, but it could also be the beginning of another pest for Knock Out and other roses. This could be significant with the large plantings of Knock Out roses in Louisiana.
7. Grape leaf skeletonizer — These small caterpillars are voracious feeders on the foliage of both wild and cultivated grapes. Heavy populations can strip the foliage from the vines in a very short period. There can be two to three generations a year. Adults can be observed from May through November and are black with an orange collar behind the head. The forewings are 4 times as long as wide and twice the area of the hind wings. The larvae are yellowish and have black bands and are about ½-inch long. Eggs are lemon yellow and are laid in clusters on the lower surface of the leaves. The life cycle takes about 66 days, and the adults are both nocturnal and diurnal. Initial signs of damage are brown, necrotic, skeletonized leaf tissue because the young larvae do not eat through the entire leaf. Later instars devour the entire leaf, leaving only the veins. Larvae feed side by side until mature, when they disperse and look for locations to pupate. Pupation will occur in leaf litter, in cracks and crevices and in trash at the base of the vines. The cluster feeding makes it easy to hand pick the young larvae and destroy them. Sprays of Bacillus thuringiensis or Sevin or Spinosad should effectively manage the populations.
Figure 8.
Till next month.
Dale
[Image: Parasite of cockroach egg cases.]
[Image: Fall armyworm on hay.]
[Image: Tachinid eggs on armyworm.]
[Image: Red headed azalea caterpillar defoliating azalea.]
[Image: Adult and nymph lantana lacebugs.] | [Image: Asian hackberry aphids.]
[Image: cerambycid in rose stem.]
[Image: Adult and larvae of grape leaf skeletonizer.]
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