Gardener's Dirt: Grasshopper population on the rise
By Jack Goodwin - Victoria County Master Gardener Edited by Charla Borchers Leon
July 14, 2011 at 2:14 a.m.
One of nature's best-dressed pests is the destructive grasshopper. Texas has about 150 species of grasshoppers, and they do tremendous damage annually to green plants, shrubs, crops and gardens. With the drought persisting this year, grasshoppers are once again on the increase in population.
Grasshoppers range in size from 1 to 4 inches, are voracious eaters and are out to get your greenery. A familiar summer noise may be heard when the male of many species attempts to attract a female by rubbing their hind femur against the lower edge of the forewing.
LAID IN FALL; HATCH IN MAY-JULY
According to Texas AgriLife Extension in an article titled "Grasshoppers and Their Control," by Carl D. Patrick and Steven G. Davis, grasshoppers lay their eggs in groups of 20 to 120 eggs per pod. They deposit eggs to 2 inches under the soil in fields, ditches, fence rows, and in crops, hay and alfalfa. Eggs are laid in the fall and lay over winter until they begin hatching in March, April and May. Hatching peaks in June but in dry weather it can continue into July.
Young grasshoppers are called nymphs. 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.
FIVE SPECIES DO 90 PERCENT OF DAMAGE
There are five species of grasshoppers, which do 90 percent of the damage each year. They and their description, with the most common listed first, are included with this article.
There are several ways to biologically and mechanically control grasshoppers, according to the source cited above. Interrupting their breeding and feeding cycles can be beneficial.
Fungus - Grasshoppers have many natural enemies that help control their population. A fungus, Entomophthora grylli, often kills many grasshoppers when weather is warm and humid. It is not much help, though, during a drought.
Protozoan - Another natural enemy is a protozoan, Nosema locustae. Its spores can be incorporated with bran to make bait such as Semaspore, Nolo Bait or Grasshopper Attack. The bait kills some young grasshoppers (nymphs), but almost no adults. Baits act too slowly and kill too few grasshoppers to be useful for immediate control.
Other bio-control options- Other natural enemies include nematodes called hairworms and insects that feed on grasshoppers, such as the larvae of blister beetles, bee flies, robber flies, ground beetles, flesh flies and tangle-veined flies. Neemix 4.5 is a commercial bio-insecticide growth regulator made from neem oil and labeled on many crops including those in gardens, on shade, fruit and nut trees, vineyards, etc.
More control options - The insecticide Sevin comes in various formulations and is labeled on many crops including turfgrass, and as with Neemix mentioned above, those in gardens, shade, fruit and nut trees, vineyards, etc. Orthene 97 is also labeled for grasshopper control in gardens and on trees. Read and follow all pesticide directions.
BIRDS AND MAMMALS
Birds (quail, turkey, larks, chickens, guineas, etc.) and mammals also eat grasshoppers, but have little effect on large populations.
One way to control grasshopper population is to eliminate sites where they might deposit eggs. They prefer undisturbed areas for egg laying, so tilling cropland or garden in mid-to-late summer discourages females. Shredding plant tissue can reduce the grasshopper food supply. Remove tall grass and weeds around your garden or plant areas, this makes the area less attractive to grasshoppers and makes it easier for birds to prey on them.
VIRUS CAN BE TRANSMITTED BY GRASSHOPPERS
Grasshoppers also cause problems to ranchers. There is a virus in cattle and horses, vesiculaar stomatitus (VSV) which can be transmitted by grasshoppers. In 2009, VSV disrupted rodeos and prompted quarantines in the Southwest United States, according to Science Daily, Sept. 1, 2009. Under laboratory conditions, plants can harbor VSV and pass the virus to grazing grasshoppers. Although it is not usually fatal, VSV causes blisters on livestock. Infected animals salivate heavily and shed the virus, which results in animal to animal transmission.
DO YOUR PART TO CONTROL THEM
Grasshoppers are on a mission to eat and multiply at the expense of gardeners, farmers, ranchers and homeowners. Let's do our part to control these pests.
The Gardeners' Dirt is written by members of the Victoria County Master Gardener Association, an educational outreach of Texas AgriLife Extension - Victoria County. Mail your questions in care of the Advocate, P.O. Box 1518, Victoria, TX 77901; or firstname.lastname@example.org, or comment on this column at www.VictoriaAdvocate.com.