Gypsy Moth, Lymantria dispar

Lymantria dispar, Gypsy moth is one of the most destructive pests of shade, fruit, and ornamental trees throughout the northern hemisphere.

It is also a major pest of hardwood forests. Synonyms of Gypsy moth is Porthetria dispar. The common names are: Asian gypsy moth (English), erdei gyapjaslepke (Hungarian), gubar (Romanian),, lagarta peluda (Spanish), limantria (Italian), lƒ¸Vstraesnonne (Danish), maimai-ga (Japanese), mniska vel’kohlava (Slovak), Schwammspinner (German), spongieuse (French).Gypsy moth is native to southern Europe, northern Africa, central and southern Asia, and Japan (Martin 2000). It also present in United States and Canada and is now present in most of northeastern N. America but its range is expanding to the south and west (Global Invasive Species Database)

Russell IPM manufactures and supplies pheromone lure, traps and complete monitoring systems for Lymantria dispar, Gypsy Moth. It is also know as onion moth. Pheromone trap data give early warning of the infestation and also exhibit the density of the insect population.

Gypsy Moth

Adult females are white with black, wavy markings ; they have robust abdomens and do not fly, and their wingspan can reach 5 cm. Egg masses are light, and the eggs inside are black and pellet like. Each mass may contain 400-600 eggs. The caterpillar is hairy, and a mature larva is 50-65 mm long with a yellow and black head. Behind the head on the thorax and abdomen are five pairs of blue spots (tubercles) followed by six pairs of brick red spots. The pupal stage is dark reddish-brown and is held in place to some object by small strands of silk. Male moths are dark buff and fly readily during the day. Eggs deposited by females during July overwinter on trees, stones, and other substrates. Eggs hatch from late April through early May with most eggs hatching by mid-May. Small first instar larvae do not feed right after they hatch and can be dispersed by wind. Young larvae feed on foliage and remain on host plants night and day. In late May when about half-grown, larvae change their behaviour and usually feed in the trees at night, and move down to seek shelter in bark crevices or other protected sites during the day. Larvae reach maturity from mid-June to early July. Migrating caterpillars are often a nuisance during the last two weeks of June. Pupation takes place during late June and early July. The pupal cases may be observed attached to tree bark, stones, buildings, and other similar sites. Adults start emerging in late June with peak emergence in mid-July. This pest produces one generation a year in Pennsylvania (PennState Dept. Ent.).

Nature of Damage

This pest is indirectly responsible for causing mortality of susceptible host trees. Heavy defoliation by the larval stage of this pest causes stress to infested host plants. Secondary organisms such as the twolined chestnut borer, Agrilus bilineatus, and shoestring root rot, Armillaria spp., successfully attack stressed trees causing mortality.Light defoliation is defined as 0 to 30% loss of foliage and has little effect on the health of trees. Defoliation is barely detectable. Moderate defoliation is described as 31 to 50% loss of foliage. At this level caterpillars may be abundant enough to be a nuisance in an area if not managed. Trees will have enough foliage remaining to stay green and little mortality is expected. Heavy defoliation is when 51% or more of the foliage is removed from a tree. Tree mortality may result from one year’s defoliation to hemlock, pine, and spruce. Deciduous trees can normally withstand one year of defoliation, but two or more successive years may result in moderate to high mortality. Around the 50% defoliation level, most deciduous trees produce auxiliary leaf buds and new foliage by mid-August. Refoliation in the same growing season creates a stress to an infested tree (PennState Drpt. Ent.).


Russell IPM manufactures and supplies pheromone lure – the Qlure, traps and complete monitoring systems for Helicoverpa armigera, African Bollworm.

Pheromone trap data gives early warning of the infestation and will also alert the user to a low level of population before it becomes serious.

The lure can be best applied with the Mothcatcher trap or Delta trap.

Lures for Pest Monitoring

Lures can be changed every 4-6 weeks to get the most accurate results.

Lures handling
Pheromone lures are a very sensitive tool. They can be affected by exposure to elevated heat and direct sunshine. Direct touching by hand may cause cross contamination leading to mixed catches in the trap. Some contaminants such as Nicotine May have repellent effect reducing trap catch.

Lure Storage

Store in a cool dry place. Shelf life can vary from 3-36 months depending on the storage temperature. See Technical Data Sheet for further details.

Trap Selection

The Deltra trap is the most sensitive trap to use for monitoring this insect. However, Moth catcher may be used in dusty conditions or in high moth population density.

Trap Density

Do not re-use the trap to monitor different insects as this may lead to mixed catches. One trap for every two hectares of large scale fields of homogenous lands.

Two traps per hectare (2trap/ha) for small holdings and in field of uneven topography.

Trap Position

Place traps near the highest point of the plant using supporting posts approximately 1 meter high, or higher if the crop is higher.

Data and Interpretation

Collect data weekly from the start of the flight of the over wintering generation. During the height of the population more frequent reading may be needed. Decisions on pesticide application should not be taken solely on the trap catch data. Climatic and biological considerations should be taken in account.