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.
| Common name | Amount per acre** | REI‡ | PHI‡ | |
|---|---|---|---|---|
| (Example trade name) | (hours) | (days) | ||
| Not all registered pesticides are listed. The following are ranked with the pesticides having the greatest IPM value listed first—the most effective and least harmful to natural enemies, honey bees , and the environment are at the top of the table. When choosing a pesticide, consider information relating to air and water quality, resistance management, and the pesticide's properties and application timing. Always read the label of the product being used. | ||||
| A. | METHOXYFENOZIDE | |||
| (Intrepid 2F) | 4.0–10 fl oz | 4 | 7 | |
| MODE-OF-ACTION GROUP NUMBER1: 18 | ||||
| COMMENTS: Early season applications: 4 to 8 fl oz; Mid- to late-season applications: 8 to16 fl oz. | ||||
| B. | CHLORANTRANILIPROLE | |||
| (Coragen) | 3.5–5.0 fl oz | 4 | 1 | |
| MODE-OF-ACTION GROUP NUMBER1: 28 | ||||
| C. | INDOXACARB | |||
| (Steward EC) | 6.7–11.3 fl oz | 12 | 7 | |
| MODE-OF-ACTION GROUP NUMBER1: 22A | ||||
| D. | BACILLUS THURINGIENSIS ssp. KURSTAKI# | |||
| (Deliver) | 0.5–2.0 | 4 | 0 | |
| MODE-OF-ACTION GROUP NUMBER1: 11A | ||||
| COMMENTS: Control is maximized by thorough coverage and by making applications when larvae are small. | ||||
| E. | SPINOSAD | |||
| (Entrust)# | 1.5–2 oz | 4 | 28 | |
| (Success) | 4.5–6 oz | 4 | 28 | |
| MODE-OF-ACTION GROUP NUMBER1: 5 | ||||
| COMMENTS: Do not apply more than 12 oz per acre per season of Success or 3.75 oz per acre per season of Entrust. For blackeyes, apply with oil. | ||||
| ** | Mix with sufficient water to obtain full coverage. |
| ‡ | Restricted entry interval (REI) is the number of hours (unless otherwise noted) from treatment until the treated area can be safely entered without protective clothing. Preharvest interval (PHI) is the number of days from treatment to harvest. In some cases, the REI exceeds the PHI. The longer of two intervals is the minimum time that must elapse before harvest. |
| # | Acceptable for use on organically grown produce. |
| 1 | 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; pesticides with a 1B group number should be alternated with pesticides that have a group number other than 1B. Mode-of-action group numbers are assigned by IRAC (Insecticide Resistance Action Committee). |