Description of the Pest
The saltmarsh caterpillar is an occasional late-season pest in some years. It is most abundant in August and September. Eggs are spherical, whitish, somewhat flattened, and are found in bare clusters (solely the eggs, no covering materials) on the undersurface of leaves. Young caterpillar larvae are hairy and gray when first hatched, and then darken to yellow, brownish, or almost black with yellow lines. Older caterpillars are covered with reddish or black hairs and can be up to 2 inches long when fully grown. Young larvae feed in groups. As they grow, they disperse from the group and feed alone on the plants.
Adult moths have a wingspan of 2 to 2.6 inches. The female is mostly white with scattered black spots and orange on the abdomen. Hind wings of males are orange instead of white.
Damage
Damage by saltmarsh caterpillar consists primarily of defoliation of plant leaves, although they have also been observed to feed on green pods.
Management
Start inspecting plants for saltmarsh caterpillar damage during the vegetative growth stage. Continue to monitor these caterpillars from bud to blossom and during the pod fill stage. Specific treatment thresholds have not been established for saltmarsh caterpillar. 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 |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
|
|
Deliver # | Application Timing Varies (See UC IPM Pest Management Guidelines and Label) | 8 |
11A |
0.5–2.0 | 4 | 0 | Control is maximized by thorough coverag... | narrow | low | low | low | short | — | — | — | — | — | 06/2018 | ||
|
|
Coragen | Application Timing Varies (See UC IPM Pest Management Guidelines and Label) | 8 |
28 |
3.5–5.0 fl oz | 4 | 1 | — | narrow | low | low | low/moderate | short | — | — | — | — | — | 06/2018 | ||
|
|
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 | ||
|
|
Intrepid 2F | Application Timing Varies (See UC IPM Pest Management Guidelines and Label) | 8 |
18 |
4.0–10 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 | ||
|
|
Entrust # | Application Timing Varies (See UC IPM Pest Management Guidelines and Label) | 8 |
5 |
1.5–2 oz | 4 | 28 | Do not apply more than 3.75 oz per acre... | narrow | low | moderate 13 | low/moderate | short to moderate 13 | very low | low | low | very low | low | 06/2018 | ||
|
|
Success | Application Timing Varies (See UC IPM Pest Management Guidelines and Label) | 8 |
5 |
4.5-6 oz | 4 | 28 | Do not apply more than 12 oz per acre pe... | 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
