Description of the Pest
Alfalfa looper and cabbage looper larvae are green caterpillars with three pairs of true legs in the front and two pairs of robust, unjointed prolegs on the abdomen (back portion of the body). A distinguishing characteristic of looper caterpillars is that as they crawl, they move their rear end up toward their heads so their body arches into a circular loop. Adult moths have dark brown, mottled forewings with a characteristic figure-eight marking in the center.
Damage
Loopers may occur at any time during the growing season. Infestations early in the season on seedling plants may result in damage to cotyledons, new leaves, and terminal buds. Looper eggs are deposited singly, usually on the underside of younger leaves. The larvae feed on larger, more mature leaves.
Management
Biological Control
Loopers have many natural enemies that frequently keep them below economically damaging levels, unless the natural enemies are killed by insecticide applications applied for other pests. Important parasitoid wasps include the tiny egg parasitoid, Trichogramma pretiosum, and four wasps that attack the caterpillars: Hyposoter exiguae, Copidosoma truncatellum, Microplitis brassicae, and Cotesia medicaginis (alfalfa looper only). In addition to the parasitoid wasps, a tachinid fly, Voria ruralis, also attacks the caterpillar. In some areas, the nuclear polyhedrosis virus, an important biological control agent, occurs naturally in fields and kills loopers. Plant habitat that attracts natural enemies and avoid the use of broad-spectrum pesticides known to harm natural enemies.
Organically Acceptable Methods
Use biological control, Bacillus thuringiensis, and the Entrust formulation of spinosad for an organically certified crop.
Monitoring and Treatment Decisions
Start inspecting plants for looper damage during the vegetative growth stage. Continue monitoring from flower bud to bloom and during the pod fill stage.
Specific treatment thresholds have not been established for loopers. Late-season infestations do not usually cause significant crop loss. If damaging numbers during mid-season results in excessive foliage loss, an insecticide application may be warranted to prevent crop loss.
Pesticides and Natural Enemy Releases
Not all registered pesticides are listed. The following are ranked by their IPM value, with the most effective and least harmful to natural enemies, honey bees, and the environment listed at the top of the table. When choosing a pesticide, consider information related to water and air quality, resistance management, and the pesticide's properties and application timing. Use PestManage to compare summarized management options for different pests in the same crop. Always carefully read the label of the product being used and take all necessary precautions when handling pesticides.
| Rank | Active ingredient | Example trade name | Group | Group Order | MoA 1 | Amount per acre | REI (hours) ‡ | PHI (days) ‡ | Comments | Selectivity 2 | Bees 3 | Predatory mites 4 | Predators 5 | Parasitoids 5 | Residue duration 6 | Leaching(fish) 7 | Adsorbed runoff(fish) 8 | Solution runoff(human) 9 | Leaching(human) 10 | Solution runoff(human) 11 | Last updated 12 |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
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XenTari # | Application Timing Varies (See UC IPM Pest Management Guidelines and Label) | 8 |
11A |
0.5–1.5 fl oz | 4 | 0 | To maximize control, ensure thorough cov... | narrow | low | low | low | short | — | — | — | — | — | 06/2018 | ||
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|
Coragen | Application Timing Varies (See UC IPM Pest Management Guidelines and Label) | 8 |
28 |
3.5–5 fl oz | 4 | 1 | — | narrow | low | low | low/moderate | short | — | — | — | — | — | 06/2018 | ||
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|
Steward EC | Application Timing Varies (See UC IPM Pest Management Guidelines and Label) | 8 |
22A |
6.7–11.3 fl oz | 12 | 7 | — | narrow | low | low | low | moderate | low | low | intermediate | very low | low | 06/2018 | ||
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|
Intrepid 2F | Application Timing Varies (See UC IPM Pest Management Guidelines and Label) | 8 |
18 |
4–16 fl oz | 4 | 7 | Early season applications: 4 to 8 fl oz;... | narrow | low | low | low | short | very low | low | low | very low | low | 06/2018 | ||
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Entrust # | Application Timing Varies (See UC IPM Pest Management Guidelines and Label) | 8 |
5 |
1.25–2 oz | 4 | 28 | Do not apply more than 3.75 oz/acre per... | narrow | low | moderate 13 | low/moderate | short to moderate 13 | very low | low | low | very low | low | 06/2018 | ||
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Success | Application Timing Varies (See UC IPM Pest Management Guidelines and Label) | 8 |
5 |
4.0-6 oz | 4 | 28 | Do not apply more than 12 oz/acre per se... | narrow | low | moderate 13 | low/moderate | short to moderate 13 | very low | low | low | very low | low | 06/2018 |
Legend
- ‡ a b Restricted entry interval (REI) is the number of hours (unless otherwise noted) from treatment until the treated area can be safely entered without personal protective equipment. Preharvest interval (PHI) is the number of days from treatment to harvest. In some cases, the REI exceeds the PHI. The longer of the two intervals is the minimum time that must elapse before harvest.
- # a b Acceptable for use on certified organic crops. Check with your certifier to confirm before application.
- 1 ↩ Group numbers for insecticides and miticides are assigned by the Insecticide Resistance Action Committee (IRAC). Insecticides with unknown modes of action are assigned mode-of-action group numbers (MoAs) that begin with UN. Rotate pesticides with a different mode-of-action group number, and do not use products with the same mode-of-action group number more than twice per season to help prevent the development of resistance. For example, the organophosphates have a group number of 1B; insecticides with a 1B group number should be alternated with insecticides that have a group number other than 1B.
- 2 ↩ Range of insect and mite groups affected by a pesticide. Broad means the pesticide affects most groups of insects and mites; narrow means the pesticide affects only a few specific groups.
- 3 ↩ Risk of harm to honey bees. For more information, see Bee Precaution Pesticide Ratings.
- 4 ↩ Risk of harm to predatory mites. Toxicities are generally to western predatory mite, Galendromus occidentalis. Where differences have been measured in toxicity of the pesticide-resistant strain versus the native strain, these are listed as pesticide-resistant strain or native strain.
- 5 a b Risk of harm to parasitoids and general predators. Toxicities are averages of reported effects and should be used only as a general guide. Actual toxicity of a specific insecticide depends on factors including the application rate, environmental conditions, and the life stage and species of a parasitoid or predator.
- 6 ↩ Length of time residue affects natural enemies. Short means hours to days; moderate means days to 2 weeks; and long means many weeks or months.
- 7 ↩ Risk of harm to fish from leaching, based on USDA Natural Resources Conservation Service Windows Pesticide Screening Tool (WIN-PST).
- 8 ↩ Risk of harm to fish from adsorbed runoff, based on USDA Natural Resources Conservation Service Windows Pesticide Screening Tool (WIN-PST).
- 9 ↩ Risk of harm to fish from solution runoff, based on USDA Natural Resources Conservation Service Windows Pesticide Screening Tool (WIN-PST).
- 10 ↩ Risk of harm to humans from leaching, based on USDA Natural Resources Conservation Service Windows Pesticide Screening Tool (WIN-PST).
- 11 ↩ Risk of harm to humans from solution runoff, based on USDA Natural Resources Conservation Service Windows Pesticide Screening Tool (WIN-PST).
- 12 ↩ Date information was last updated in the UC IPM Pest Management Guidelines.
- 13 a b c d Toxic to some natural enemies (lacewing and syrphid fly larvae, predatory beetles, and thrips) when sprayed and up to 5 to 7 days after.
UC IPM Pest Management Guidelines: Dry Beans
UC ANR Publication 3446
R.F. Long (emeritus), UC Cooperative Extension Yolo County
P.B. Goodell (emeritus), UC IPM and Kearney Agricultural Research and Extension Center, Parlier
Acknowledgement for Contributions to Invertebrates
L.D. Godfrey, Entomology, UC Davis
