March of the Armyworms

The fall armyworm, Spodoptera frugiperda, eats foliage of many different kinds of plants, such as turfgrass, shrubs, and agricultural crops. Several reports of these armyworms have been seen in large populations as they march in and feed both day and night, causing circular or irregular deadened patches of turfgrass. Armyworms do not usually kill lawns, especially bermudagrass lawns, but will scalp them; however, St. Augustine lawns are more susceptible, and can be completely lost after armyworms feed.
Armyworms have four life stages: egg, larva, pupa and adult. The eggs are very small, and are laid on leaves at night. The larvae hatch from the eggs and feed mostly at night. They tend to hide in thatch and debris in the daytime. The young larvae are white with black heads but develop a prominent white line forming an inverted “Y,” with stripes along the body as it matures. The larvae will become 2 inches in length before entering the soil to pupate. Then the adult moths emerge, mate and lay eggs. The adult moth has a wingspan of 1 ½ inches, with silver-white hindwings and dark grey front wings with light and dark splotches.
The locations of large populations of armyworms vary each year throughout the state. However warm, humid climates, along with large amounts of thatch are favorable conditions for fall armyworms to multiply. Armyworms should be controlled when they occur in large numbers or plant damage becomes excessive.

Some Control Options:

Some Non-Chemical Control Options:
Eliminate thatch to reduce develop sites of the armyworms. Also monitor for sites of infestation in the turfgrass by flushing the area with soapy water if damage is seen but the armyworms are not seen. This will cause caterpillars to move around within minutes so they can be spotted.

Some Chemical Control Options: Armyworms can be controlled using such insecticides containing the active ingredients permethrin, cyfluthrin, bifenthrin or esfenvalerate. Spot treatments or whole lawn treatments can be effective, depending on the size of the population.

Photo of fall armyworm. Photo by Bart Drees, Professor and Extension Entomologist, Texas A&M University.

Are Leafcutter Bees Making Holes in Your Leaves?

Most common leafcutter bees, Megachile sp., are the same size as honey bees. However, leafcutter bees are mostly black in color with light colored bands across their abdomens. Also, female leafcutter bees carry pollen on stiff hairs on the underside of the abdomens rather than on the sides of the hind legs like honey bees. Leafcutter bees tend to be non-aggressive and usually only sting when handled.
Leafcutter bees are solitary bees, so individual female bees dig out nesting areas, create nest cells and provide young with food. Adult females cut circular or elongate pieces of leaves from such plants as roses, azaleas, bougainvilleas, redbuds, and other cultivated and wild plants. They use the leaves to construct walls and partitions for nesting cells. These nests can be found in such places as hollow twigs, holes in buildings, and in the ground. The nesting cells are provided with nectar and pollen collected from flowers. One egg is laid in each nesting cell. When the egg hatches, a white, legless, grub-like larva emerges and develops within the cell. The larva then pupates before emerging as an adult out of the cell the next season.
Leafcutter bees are important pollinators of plants. However, they can cause damage to plants when large populations exist on smaller, developing plants.

Control Options:
There are many natural enemies of leafcutter bees such as parasitic bees and wasps, velvet ants and some blister beetles. The use of insecticides is usually ineffective for the prevention of leaf cutting. One control option is to cover susceptible plants with cheesecloth or other loose netting during periods when leafcutter bees are most active. Also, leafcutter bee populations can be reduced if breeding sites are eliminated so such items as rotting boards or thick stemmed plants with hollowed openings should be removed from the landscape.

A leafcutting bee, Megachile sp. (Hymenoptera: Megachilidae), adult. Photo by Bart Drees, Professor and Extension Entomologist, Texas A&M University.

Fall Webworms Are Likely to be Found Soon

The fall webworm, Hyphantria cunea (Drury), is usually noticed when the light gray silk webs are discovered on trees in late summer and early fall. They are considered pests of shade and ornamental trees in urban areas, by attacking more than 88 plants as they enclose leaves and small branches with their webs. Four generations occur in the south Texas, with 2 to 3 generations occurring in northern Texas. The last generation in the fall is usually the most damaging.
The caterpillars build webs soon after hatching and they will remain inside the web consuming the tender parts of the leaves. If the caterpillars eat all of the leaves within the web, then new foliage will be enclosed within the webbing. These caterpillars are 1 inch in length, pale yellow or green in color, and covered with white and black tufts of long hair. The caterpillars will molt 6 or 7 times before dropping to the ground to pupate. The pupae overwinter and the adult moths emerge the following spring.

Some Control Options:
Some Non-Chemical Control Options:
1)Small webs can be removed by pruning and destroying the infested portions of branches.
2) A stick or pole can be used to snag individual webs to allow natural enemies such as yellow jackets, paper wasps and birds to eat the webworms.
3)Bacillus thuringiensis, B.t,. is effective against fall webworms if it is applied when the caterpillars are small. It is better to apply after the eggs hatch and the web is not so dense.

Some Chemical Control Options:
Chemicals should be applied after eggs hatch, since they are most effective on young caterpillars. Insecticides such as those containing spinosad and tebufenozide as active ingredients can be used. Multiple applications may be needed as generations continue.

Fall webworm, Hyphantria cunea (Drury) (Lepidoptera: Arctiidae), web on pecan. Photo by Bart Drees, Professor and Extension Entomologist, Texas A&M University.