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Grasshoppers

Article author: Pat Porter
Most recently reviewed by: Ed Bynum (2018)

Common Name(s): Differential Grasshopper, Grasshoppers, lubber grasshopper, migratory grasshopper, Packard grasshopper, red-legged grasshopper, two-striped grasshopper

Description

Grasshoppers undergo gradual metamorphosis as the nymphs (immature insects) molt to the next growth stage. This means that nymphs look very much like adults, except that the nymphs do not have fully developed wings. If a grasshopper’s wings are fully developed, then it is an adult. The long hind pair of legs is well adapted for jumping, and adults are good fliers over short distances.

There are many color variations according to species, and many species are well camouflaged and difficult to see unless they move. Other species are brightly colored.

All grasshoppers have mandibles (teeth) and damage plants by chewing chunks of tissue from leaves and other plant parts. The feeding usually begins on outside edges of leaves and the chewed area has ragged or irregular edges. This often looks quite different from the smoother, more even damage done by caterpillars.

 

Origin and Distribution

Grasshoppers are distributed worldwide and occasionally reach serious pest outbreak status causing major crop loss. Occasionally, large flights of grasshoppers are detected on radar.

Habitat & Hosts

Almost any type of plant including corn, alfalfa, Bermudagrass, cotton, millet, peanut, rice, ryegrass, sorghum, Sudangrass, soybean, sugarcane, vegetables, wheat, flowers and landscape plants.

Life Cycle

Grasshoppers deposit their eggs 1⁄2 to 2 inches below the soil surface in pod-like structures. Each egg pod consists of 20 to 120 elongated eggs cemented together. The whole mass is somewhat egg-shaped. Egg pods are very resistant to moisture and cold and easily survive the winter if the soil is not disturbed.

Eggs are deposited in fallow fields, ditches, fencerows, shelter belts and other weedy areas, as well as in crop fields, hay fields and alfalfa. Eggs begin hatching in late April or early May. Hatching peaks about mid-June and usually ends by late June. If spring weather is cool and extremely dry, hatching may be delayed and continue into July.

Young grasshoppers are called nymphs, and they undergo simple metamorphosis. They look like adults, but are smaller and have wing pads instead of wings. Nymphs go through five or six developmental stages and become adults in 40 to 60 days, depending on weather and food supplies. The adults of grasshopper species that damage crops become numerous in mid-July and deposit eggs from late July through fall. Usually only one generation of grasshoppers is produced each year.

Grasshoppers have a high reproductive capacity. The female lays an average of 200 eggs per season, and sometimes as many as 400 eggs. If favorable weather increases the number of eggs, the grasshopper population may be dramatically larger the following year. Grasshoppers cause some damage every year, but they become very destructive during outbreaks. The main factor affecting grasshopper populations is weather. Outbreaks, or exceptionally large populations, are usually preceded by several years of hot, dry summers and warm autumns. Dry weather increases the survival of nymphs and adults. Warm autumns allow grasshoppers more time to feed and lay eggs.

Management

If you live in the State of Texas, contact your local county agent or entomologist for management information. If you live outside of Texas, contact your local extension for management options.

Nosema locustae is a protozoan that can be purchased commercially to treat large areas. Its spores have been incorporated with bran to make insecticide baits such as Semaspore®, Nolo Bait® or Grasshopper Attack®. These baits kill some nymphs but almost no adults, though infected adults lay fewer eggs. Baits act too slowly and kill too few grasshoppers to be useful for immediate control.

When grasshoppers are at low numbers, handpicking them is an option. However, when at high numbers control becomes very difficult and insecticides are warranted.

Home garden control options include:

  • Carbaryl (Sevin)
  • Neem
  • Pyrethrins
  • Synthetic pyrethroids

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Thrips

Article author: Kerry Siders

Common Name(s): Thrips

Pest Location

Row Crop, Vegetable and Fruit

Description

Thrips are slender, cigar-shaped, straw-colored insects about 1/15-inch-long. They have piercing and sucking, cone-shaped mouthparts. Adults have narrow wings fringed with hairs and can drift long distances in the wind.

 

Figure 9. Immature thrips.

Figure 9. Immature thrips. Photo by Dr. David Kerns, Professor, IPM Coordinator and Extension Specialist, Texas A&M AgriLife Extension, College Station

Habitat & Hosts

Western flower thrips feed on a wide variety of plants including chrysanthemums, gloxinia, impatiens, tomato, vegetables and grasses. Some plants species, varieties and cultivars are more attractive to the thrips than others.

Thrips feeding on plant. Photo by George Markin, USDA Forest Service, Bugwood.org

Photo by George Markin, USDA Forest Service, Bugwood.org

Life Cycle

In the thrips life cycle, egg-to-adult development takes about 16 days: Eggs inserted into the plant tissue by the female’s sharp egg-laying tube (ovipositor) hatch in about 6 days. Two larval stages require about 6 days for completion; then, the prepupal and pupal stages take an additional 4 days. The average life span of a mated female is about 35 days, and each female can produce fifty or more eggs. Thrips can reproduce without mating. Mated females produce both males and females; unmated females produce only males.

Management

If you live in the State of Texas, contact your local county agent or entomologist for management information. If you live outside of Texas, contact your local extension for management options.

Cultural management. Avoid planting cotton during cool conditions so that young plants will not be affected when plants are most susceptible to thrips damage. Not planting cotton near small grains and onions helps alleviate thrips migration into the field.

Biological control. Many small predators such as predaceous thrips, minute pirate bugs, and spiders feed on thrips. Since thrips enter the field during and soon after plant emergence, these predators are usually not present in high enough numbers to control a thrips infestation. However, these control agents help reduce thrips numbers at the infestation source, such as small grains and weeds, before they migrate into the cotton field.

Chemical control and action threshold. Consider using in-furrow systemic insecticides or seed treatments in areas with a history of frequent, heavy thrips infestations. Where in-furrow or seed treatments have been used, base subsequent applications of foliar insecticides on the action threshold and occurrence of thrips larvae. The appearance of larvae indicates that the preventive insecticide is no longer inhibiting thrips colonization. Research shows that applying foliar sprays after significant thrips damage has occurred does not result in increased yields. Base your decision to apply insecticide on the number of thrips present and the plant development stage.

Related Publications

http://lubbock.tamu.edu/files/2017/05/Thrips_ENTO-069.pdf

Citations

Suhas Vyavhare, Assistant Professor and Extension Specialist David Kerns, Professor, IPM Coordinator and Extension Specialist. ENTO-069. 2017. Thrips. Texas A&M AgriLife Extension

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Southern corn rootworm


Most recently reviewed by: Janet Hurley & Pat Porter (2018)

Common Name(s): Southern Corn Rootworm, spotted cucumber beetle

Pest Location

Row Crop, Vegetable and Fruit

Description

The adult is about 1/4-inch long, yellow-green with a black head and antennae. There are twelve black spots on the wing covers (elytra). The larva (rootworm) is cream colored and about 3/4-inch long when fully developed, with a brown head capsule and bearing three pairs of short legs.

There are several other common Diabrotica species in Texas: 1) the western corn rootworm, C. virgifera virgifera LeConte, a pest of corn in the High Plains that can be recognized by adult beetles having a solid pale green elytra and with no dark edge on the upper part (femur) of the hind leg; 2) the Mexican corn rootworm, D. virgifera zea Krysan & Smith, a pest of corn in central and south Texas with adults having a solid pale green elytra that may be marked with faint stripes, and with a dark edge on the hind femur; and, 3) the banded cucumber beetle D. balteata LeConte, common in soybeans (larvae feed on soybean roots) and some vegetables with the elytra of adults being bright green transverse yellow bands; the northern corn rootworm, D. barberi Smith & Lawrence, occurs in the Texas panhandle.

Adult beetles feed on leaves and flowers of some plants and larvae feed on roots of corn, sorghum and other plants; medically harmless.

 

Habitat & Hosts

Both adults and larvae (rootworms) have chewing mouthparts. Injury to corn and sorghum occurs in the seedling (6 to 9 leaf) stage of plant development. Larvae chew along roots, excavating grooves and tunnels. Often, the larvae tunnel directly into the base of the stalk, stunting plant growth or killing entire plants, thereby reducing plant stands and yield. Adult beetles feed on a wide variety of plants including leaves and flowers of vegetables (beans, cucurbits) and ornamentals. This is one of the most common beetles found in the home garden and flower beds. Adults can be found on wildflowers or legumes.

Corn rootworm larvae.

Corn rootworm larvae. Patrick Porter

Life Cycle

Adult beetles overwinter and become active in the spring, feeding on a wide variety of host plants including weeds and grasses. They enter corn and sorghum fields soon after plants emerge and lay eggs in the soil. Eggs hatch in 5 to 11 days and young larvae crawl through the soil and feed on roots of corn, sorghum or other hosts. Larvae develop through three stages (instars) in 10 to 16 days before pupating and then emerge as adults after 5 to 12 days. Thus, the development takes 20 to 39 days, depending on soil temperature.

Southern corn rootworm has several generations per year while western and Mexican corn rootworms have only one generation per year.

Management

If you live in the State of Texas, contact your local county agent or entomologist for management information. If you live outside of Texas, contact your local extension for management options.

See Vegetable IPM.

Control of larvae is seldom practical in home garden situations.

Genetically modified corn that contains Cry toxins for rootworm control is largely ineffective on southern corn rootworm, although corn and sorghum growers can use registered soil-applied insecticides at planting.

Managing Insect and Mite Pests of Texas Corn

Managing Insect and Mite Pests of Texas Sorghum

 

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