European Pepper Moth (Dufo Moth)

This insect was first found in California in 2004 and now occurs in much of the state. The life stages of European pepper moth (family Crambidae) are egg, larva, pupa, and adult.

Adults can fly and move with the wind long distances. They are 1/3 to 1/2 inch long with a wingspan of 4/5 inch. Adults are mostly brown to dark olive with bands on the abdomen and pale grayish or yellowish to white lines on the forewings; at rest the pale markings orient mostly perpendicular to body length. A distinguishing marking is the finger-shape (sharp curve) in the outer- or rear-most pale line of each forewing pointing to the rear. At rest the abdomen of males extends beyond the wings and the tip (rear end) curves distinctly upwards.

Eggs are flattened, oval, and about 1/35 inch (0.7 mm) long. They occur singly or in a group of several laid overlapping, mostly on the underside of leaves near veins. Eggs may also occur on the upper side of leaves or on stems or soil. They are pale green or yellowish to whitish when laid, then darken to pink, reddish orange, and then brown before hatching.

Larvae (caterpillars) grow 3/4 to 1-1/4 inches long. They are creamy whitish to pale or dark brown with a dark brown head and prothoracic shield (area on top immediately behind the head). The abdomen and thorax have rows of brown to grayish, slightly raised bumps (tubercles) each with one or two short bristles. Larvae produce thin, silken strands on chewed foliage, the base of stems, and other plant parts and on soil and plant debris in and near containers.

Pupae are yellowish brown and 3/4 inch long or less. They occur enclosed in cocoons composed of chewed plant parts, frass (excrement), and soil particles webbed together. Cocoons are attached to the bottom and sides of plant containers, the underside of lower leaves, and on growing media, plant debris, and topsoil.

Egg to adult development (1 generation) occurs in 6 to 8 weeks when temperatures average 68°F; 3 to 4 weeks of this time are as feeding larvae. There can be 8 or 9 generations per year in California. In greenhouses and outdoor nurseries where winters are mild, larval feeding and all life stages can occur throughout the year.

Larvae chew buds, flowers, fruit, leaves, roots, and stems; they especially cause pits and holes in lower leaves. When abundant the larvae tend to feed higher in the plant. Damaged leaves may drop prematurely or wilt. Larval chewing on the basal stem sometimes girdles (entirely surrounds) the stem, killing the plant.

Several dozen floriculture and nursery crops are hosts in Southern Europe and the Mediterranean region where European pepper moth is native. In cooler locations such as Canada and northern Europe it primarily is a pest in greenhouses. In southern California, damage has been observed in the field and in greenhouses on begonia, echinacea, gerbera, kalanchoe, and poinsettia. In roses it feeds primarily on fallen leaves and other crop debris.

Cultural controls and insecticide application are important management practices. The potential effectiveness of biological control for European pepper moth in California is unknown.

Natural enemies of European pepper moth include predaceous ground beetles and soil-dwelling predatory mites, such as Hypoaspis and Stratiolaelaps spp. Trichogramma spp. wasps parasitize the eggs. The caterpillars are attacked by various parasitic wasps. For parasites and predators to potentially be effective, avoid applying broad-spectrum, persistent insecticides, especially early in the crop production cycle. Control ants, reduce dustiness, and use only selective and semi-selective insecticides where feasible. For more information see Biological Control, Protecting Natural Enemies and Pollinators, and Relative Toxicities of Pesticides Used in Floriculture and Nurseries to Natural Enemies.

European pepper moth is a scavenger that feeds on almost any decaying or dropped plant debris, as well as directly on plants. Practice excellent sanitation to help limit its reproduction and spread. Control weeds, keep plant production areas clean, and promptly remove and dispose of crop debris in covered containers.   

Remove the lowest leaves of hosts, especially those touching the surface of growing media, to reduce pest abundance and survival. For example, during regular monitoring, clip or pinch off and inspect the lowest leaves of each plant sampled. This also helps guide monitoring during subsequent dates by visually indicating which plants were previously inspected; during subsequent sampling, inspect different plants and clip off any leaves touching media. The underside of lowest leaves is especially difficult to cover when applying insecticide and this practice will improve coverage and the effectiveness of pesticide applications.

Avoid crowding plants; space containers so that foliage does not touch adjacent plants. Adequate spacing inhibits caterpillar movement between plants, facilitates more thorough foliage coverage when spraying pesticides, and reduces relative humidity within canopies. European pepper moth is native to marshlands (wetlands) and thrives under moist conditions.

Exclude migrating adults by covering greenhouse openings with screens of sufficient surface area to allow adequate ventilation. Screen and isolate individual flats to exclude adults and larvae from seedlings; larvae can also move from nearby hosts to infest new plants. Use row covers or exclusion netting to exclude moths from field crops, ensuring the cover is held above plant surfaces to eliminate oviposition on leaves contacting the material. Ensure covers and screens are properly maintained.

Biological and cultural controls are organically acceptable management methods. The botanicals azadirachtin, neem, and pyrethrins without piperonyl butoxide (PyGanic), entomopathogenic nematodes (Heterorhabditis and Steinernema spp.), and the microbial insecticides Bacillus thuringiensis ssp. aizawai, Bt ssp. kurstaki, and certain spinosad formulations (Entrust Naturalyte, Entrust SC) are acceptable for organic production.

Examine hosts at least once a week for caterpillars and their chewing damage, frass (excrement), and webbing. Randomly select plants throughout the growing area. Focus inspections for European pepper moth on the basal stems and the surrounding soil, bottoms and sides of containers, crop debris in and around containers, and especially the underside of lower leaves.

Pheromone-baited water traps are highly attractive to adult males, followed by sticky, delta traps, and funnel traps that attract and capture the adults. Bait traps with the species-specific pheromone as directed by product suppliers.

Larvae

Target early instars, regardless of the product applied, as they tend to be more susceptible and exposed to treatment. Adding narrow-range oil to the mix will kill eggs contacted directly and help to improve foliage coverage for larval control. Adding a narrow-range oil to spinosad where conditions and labels allow increases translaminar movement into plant tissue and efficacy. Applying selective (Bt) or semi-selective products (e.g., spinosad) early during the crops' production conserves natural enemies and can reduce the development of pesticide resistance. Reserve application of broad-spectrum, persistent insecticides such as organophosphates and pyrethroids for later in the production cycle.

Adults

Focus on excluding adults from growing areas and particular groups of plants. Adults can be controlled by fogging or spraying a labeled persistent, broad-spectrum contact insecticide. Sprays must be expertly applied directed to thoroughly wet the underside of foliage with high volume and large droplet size, especially the underside of lowest leaves. Adult moths do not feed and must be directly contacted. Aerosols or fogs applied in closed greenhouses during late afternoon before the night-flying adults become active are also effective. After any adulticide application, turn off any night lighting in treated greenhouses for as long as compatible with the crops' production.

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