OVERTON A dry, mild winter has encouraged a large hatch of grasshoppers in Central Texas, with heavy infestations already being seen in some East Texas counties.
“We don’t have numbers yet, but we’re hearing reports of Central Texas farmers finding the ground under their feet squirming with grasshopper nymphs,” said Dr. James Robinson, entomologist with Texas Cooperative Extension.
Robinson said reports of large grasshopper populations are ranging from Dallas to McGregor and College Station. He has also received reports of infestations in the Athens and Canton areas.
Farmers are justifiably concerned about the infestations because with soil moisture already below normal in many parts of the state, hay and forage could be at a premium during the months ahead, he said.
Though the grasshoppers are small, many farmers are electing to treat early. It’s an expense, but one that is probably wise, considering the past effects of adult grasshoppers on pastures.
In the spring of 2000, when there was also a dry mild winter, Texas A&M entomologists estimated pasture losses alone at $190 million. In 1998, a drought year, the impact of grasshoppers on improved pastures was also catastrophic.
Grasshopper hatches are normally held in check by a fungus that attacks their over-wintering eggs in the soil. During a dry winter, the fungus does not flourish and more grasshopper eggs hatch to become nymphs.
Producers are usually advised that it becomes economical to treat when they can count 25 grasshoppers per square yard. Twenty-five grasshoppers may not sound like a big number, but over an acre, this count could equal 120,000 grasshoppers. At this concentration, the grasshoppers can eat as much forage as a mature cow.
Chemical controls for grasshoppers in improved pastures are relatively cheap when products are used at their lowest rates. Sevin XLR and Malathion 57 EC have proven effective on grasshoppers nymphs in bermudagrass pastures at their lowest rates. Cost of these products ranges from $1.40 to $4.35 per acre.
Which insecticide used depends upon more factors than cost, however. Malathion has no grazing or harvest restrictions. Sevin has a 14-day grazing restriction.
The highly toxic insecticide methyl parathion is also labeled for grasshopper control. Because of its toxicity level, Robinson recommended that it be applied either aerially or by a commercial applicator using an enclosed cab machine.
“I do not recommend that methyl parathion be applied by farmers with an open air tractor cab and spray rig. It’s just too dangerous,” Robinson said.
Methyl parathion has a 15-day waiting period for hay harvesting and grazing.
Dimilin can be used for control of grasshopper nymphs in rangeland. There will not be a special permit allowing the use of this product on pastureland.
“The choice of insecticides for grasshopper nymphs in pastureland remains to be carbaryl (Sevin), malathion or methyl parathion,” Robinson said.
He emphasized that insecticide products are complicated and allowed usage will vary among formulations of the same chemical. Applicators should read the label carefully before mixing or applying. For example, producers should note that the restrictions listed above are for beef cattle only. Restrictions for use on dairy pastures vary considerably.
Sevin, a commonly used insecticide, has another restriction. It can only be used twice in a calendar year. In addition to controlling grasshoppers, it is also effective with another scourge of East Texas pastures, the fall armyworm, which has been a problem in recent years.
“Thus, they might consider using one of the other products for grasshoppers now and holding Sevin in reserve in case they have a problem with armyworms this fall,” Robinson said.
Home gardeners shouldn’t worry about grasshoppers damaging lawns. Vegetable gardens and ornamental landscape plants can be a target, however. For safe control in vegetable gardens, use Sevin or malathion.
Insecticides containing a pyrethroid can be used on ornamentals but should not be used on vegetable crops.
Robinson has put together a fact sheet on the various grasshopper control products and their formulations and distributed it to county agents throughout East Texas. Producers needing more specific information are advised to contact the Extension offices in their counties.
To contact your local county agent, check your local phone book or visit the East Texas District 5 Extension site at http://overton.tamu.edu/d5.
-30-