HPIPM:Grasshoppers and Crickets
Author:Sue Blodgett, Frank B. Peairshttp://bspm.agsci.colostate.edu/people-button/faculty/frank-peairs/] revision (Michael J. Brewer, Frank B. Peairs & Jay D. Donahue original)
Grasshoppers are a complex of several species with various emergence dates. Both immatures and adults are foliage feeders. Grasshopper populations are strongly influenced by climate; long, warm fall weather and warm, dry springs favor grasshopper population increase.
The following website provides a comprehensive source of information on grasshopper biology, ecology, identification and management of grasshoppers and crickets in North America. [1]
Monitoring
Hazard Maps are developed each year as a cooperative effort of USDA-APHIS-PPQ and are available at the following site. http://www.sidney.ars.usda.gov/grasshopper/http://www.sidney.ars.usda.gov/grasshopper/
Management
Table 1. Treatment thresholds for immature and adult grasshoppers (from University Minnesota)
| Rating | Immatures/yd2 | Adults/yd2 | ||
|---|---|---|---|---|
| Margin | Field | Margin | Field | |
| Light | 25-35 | 15-25 | 10-20 | 3-7 |
| Threatening | 50-75 | 30-45 | 21-40 | 8-14 |
| Severe | 100-150 | 60-90 | 41-80 | 15-28 |
| Very Severe | 200+ | 120+ | 80+ | 29+ |
Treat crop borders when immatures are small and numbers are moderate. Timing of grasshopper control depends on the potential for crop loss, crop value, size (stage) of grasshoppers present. Grasshopper control is most effective before the insects become large nymphs or adults, as these stages are more mobile and more difficult to control.
Chemical control may be justified when adult grasshopper populations are threatening, according to the population densities shown in Table 1. Re-infestation originating from outside the field may occur after 10 to14 days. Use the higher dosages for adults, lower for the more immature. Sufficient gallonage is important. See A Guide to Grasshopper Control in Cropland in this guide for more information
Product List for Grasshoppers:
| Insecticide | Product per Acre (Fl oz. or oz. product) | Preharvest Interval, remarks |
|---|---|---|
| FastacR,1,2 | 2.2 - 3.8 | 3 days. 12 hr REI. Extremely Hazardous to Bees! Do not apply to alfalfa in bloom. No more than 3.8 fl oz per cutting, 11.4 fl oz per season. |
| Beauveria bassiana1,2 | See labels | 0 days. 4 hr REI. Potententially pathogenic to bees; avoid applying where bees are foraging or around hives. |
| Baythroid XLR,1 | 2.0-2.8 | 7 days. 12 hr REI. Extremely Hazardous to Bees! Do not apply to alfalfa in bloom. Maximum of 2.8 oz per acre applied per cutting. Total 11.2 oz/A applied per season. |
| carbaryl1,2 | See labels | 7 days. 12 hr REI. Most formulations are Extremely Hazardous to Bees! Do not apply to alfalfa in bloom. Sevin XLR+ is safe for bees if applied at <1.5 lbs ai/acre when no bees are in the field. Do not apply more than once per cutting. Bait formulations are also available. |
| Prevathon | 14-20 | 0 days. 4 hour REI. 1 application per cutting, do not apply more than 0.2 lb ai/acre/crop. |
| chlorpyrifos 4ER,1,2 | See labels | 7-14 days rate dependent. 24 hr REI. No more than one application per cutting or 4 applications/yr. Extremely Hazardous to Bees! Do not apply to alfalfa in bloom. Minor phytotoxicity may occur |
| chlorpyrifos + gamma cyhalothrinR,1,2 | See labels | See labels for preharvest intervals and specific use restrictions. 24 hr REI. Extremely Hazardous to Bees! Do not apply when bees are present. |
| Cobalt AdvancedR,1 | 6-13 | 21 days. 14 days to graze. 24 hour REI. See labels for additional restrictions for individual active ingredients. Extremely Hazardous to Bees! |
| cyfluthrinR,1,2 | See labels | 7 days. 12 hr REI. Extremely Hazardous to Bees! Maximum of 0.05 lb a.i./acre applied per cutting and total 0.2 lb ai/acre applied per season. Do not apply to seed alfalfa. |
| dimethoate1,2 | See labels | 10 days (harvest, grazing). 48 hr REI. Extremely Hazardous to Bees! Do not apply to alfalfa in bloom. 1 application/cutting. |
| gamma cyhalothrinR,1,2 | 2.56-3.84 | 7 days for hay. 24 hr REI. Extremely Hazardous to Bees! Do not apply to alfalfa in bloom. Do not apply more than 0.24 pt /A per cutting. Do not apply more than 0.96 pt/A per season. Advisable to move bees during application and allow 3 (low rate) or 5 (high rate) days before re-introduction of bees |
| lambda cyhalothrinR1,2 | See labels | 7 days for hay. 24 hr REI. Extremely Hazardous to Bees! Do not apply to alfalfa in bloom. Do not apply more than 0.03 lb a.i./A per cutting. Do not apply more than 0.12 lb ai/A per season. Advisable to move bees during application and allow 3 (low rate) or 5 (high rate) days before re-introduction of bees |
| BesiegeR | 6 - 9 | 1 day for forage, 7 days for hay. 24 hr REI. Make applications when bees are not actively foraging by applying during early morning or evening hours. See labels for additional restrictions for individual active ingredients. Do not apply more than 9 fl oz product per cutting or 31 fl oz per season. |
| malathion2 | See labels | 0 days. 12 hr REI. Not effective below 65oF. Apply to blooming alfalfa only in evening or early morning when bees are not working. |
| malathion ULV2 | 8 | 0 days. 12 hr REI. Extremely Hazardous to Bees! Do not apply when alfalfa is in bloom. Do not apply to seed alfalfa. |
| zeta cypermethrinR,1,2 | See labels | 3 days. 12 hr REI. Extremely Hazardous to Bees! Do not apply to alfalfa in bloom. No more than 4 oz per cutting, 12 oz per season. |
| StallionR,1 | 9.25 - 11.75 | 7 days. 24 hr REI. Extremely Hazardous to Bees! Do not apply to alfalfa in bloom. See labels for additional restrictions for individual active ingredients. No more than 11.75 oz per cutting, 35.25 oz per season |
| RRestricted use pesticide 1Labeled for chemigation 2Generic active ingredient, several formulations. | ||
The information herein is supplied with the understanding that no discrimination is intended and that listing of commercial products, necessary to this guide, implies no endorsement by the authors or the Extension Services of Nebraska, Colorado, Wyoming or Montana. Criticism of products or equipment not listed is neither implied nor intended. Due to constantly changing labels, laws and regulations, the Extension Services can assume no liability for the suggested use of chemicals contained herein. Pesticides must be applied legally complying with all label directions and precautions on the pesticide container and any supplemental labeling and rules of state and federal pesticide regulatory agencies. State rules and regulations and special pesticide use allowances may vary from state to state: contact your State Department of Agriculture for the rules, regulations and allowances applicable in your state and locality.
