IPM – Insect Pest Scouting and Management – Late May 2018

These insects, some pests, some beneficial were noted from scouting efforts in central Ohio from mid-May to early June 2018.

Imported Cabbageworm

One of the most common predators of the brassicacea family of vegetables is the larval form of the cabbage white butterfly, called the imported cabbageworm. The butterfly is a constant presence in Ohio as our most common butterfly species. It lays eggs on cabbage family plants and the larval forms feed on the foliage. They can be difficult to spot due to coloration but feeding damage and frass (fecal material) can be observed via scouting.

The focus is on the cabbageworm fecal material, called frass, at the base of the leaf in the bottom of the picture. The cabbageworm can be difficult to locate due to camouflage but the frass and pattern of leaf damage indicates to keep looking to locate the predator.

The butterfly lays very tiny eggs a single egg at a time on the leaves using her ovi-positor.

Egg size with penny added to picture for reference.

Control is by scouting for eggs, which can be difficult, or for by early recognition of larvae and damage. Hand removal is very effective for small plantings. Organic control (check the label carefully) is possible with spinosad products.

Virginia Fact Sheet on Spinosad

Imported Cabbageworm Fact Sheet

Cucumber Beetles

Cucumber beetles are a major pest in vegetable plantings. The adults have emerged from their over wintered areas to start feeding on plants and laying eggs in the soil at the base of cucurbit family plants.

Feeding damage to the cotyledons and early true leaves of the cucurbit family from over-wintered cucumber beetle adults prior to egg laying.

Cucumber beetles are a serious pest of cucurbit family plants due to feeding on foliage, flowers and fruit. Control can be difficult. They also vector a devastating bacterial wilt disease that can quickly kill plants and has no treatment.

Cucumber Beetle Fact Sheet

Egg Scouting

A good habit to use when scouting for insect pests on plantings is to look at the underside of the leaves for eggs. Many of the insect pests lay eggs singly or in clusters on the underside of leaves, where if undetected, will hatch into larvae that will feed on the foliage. This egg cluster was noted on oregano. I suspect these eggs to be from Box Elder bugs, which do not normally feed on oregano. Both a Box Elder and related Sugar Maple are in the vicinity of the oregano planting.

Slugs

Slugs will be more numerous in production areas that have high organic matter content. They can feed and damage foliage. Early control is critical to avoid build up and infestation of a production area during a growing season.

Control of slugs can be achieved with organic products containing iron phosphate. Slug Factsheet from PSU

Cutworms

This is the larval form of a night moth. It curls up around the stem of a plant and feeds until the stem is cut in half and the plant has been killed. They feed at night commonly so a grower would notice a dead plant that looks cut in half. Digging around the base of the plant can sometimes find the causative agent.

Dusky Cutworm. Found when digging around base of dead cucurbit plant.

Cutworm Fact Sheet

Ground Beetle – Beneficial

Not all insects are pests, some are beneficial and are feeding on pest and assisting the grower. Proper identification will allow the backyard grower, community gardener and urban farmer to know what to keep and what to treat.