Gypsy Moth, Lymantria dispar originally came from Europe & Asia during the 19th century. Despite efforts to control them with predators and sprays they continue to wreak havoc by defoliating hardwood forest canopies. Host trees can include: Oak (Quercus), Birch (Betulus) and Aspen (populus) in the north, to various hardwoods such as Sugar Maple (Acer saccharum) American beech (Fagus grandifolia) and softwoods such as Eastern White pine (Pinus strobus) and Colorado blue spruce (Picea pungens) in southern Ontario. Adults are active during mid-summer laying eggs. Here’s how you can recognize them:
Females – wingspan of 5 cm, Light coloured with dark markings and CAN”T FLY!
Males – wingspan of 2.5 cm; brown in colour and DO FLY.
Caterpillars- have 5 pairs of blue dots and 6 pairs of bright red dots. Early instars look very similar but the dots are less visible (see photo).
Lifecycle: This includes: egg, larva (several instars), pupa and adult
If you see caterpillars venturing up your trees, install a burlap wrap around tree trunk. Here’s an instructional video.
If you have a large forest canopy on your property you may want to install pheromone traps to catch and confuse male moths.
Search your property for for Egg Masses: The best time to search for egg masses on trees is after the leaves drop off the trees in fall as they’re easier to find. However you can look for them at anytime from early summer through to the following spring. Look for them in sheltered locations such as:
- under branches or patio furniture;
- on rocks, firewood, fences or windowsills,
- under the eaves, near bird houses or mail boxes.
Do not simply scrape the egg mass off and let it drop to the ground as the caterpillars may still hatch. Here’s how it’s done:
- Spray the mass with water to stop the egg mass from crumbling.
- Scrape the mass with a stick or any object with a flat surface such as a knife or paint scraper into a container (i.e., brown paper bag) and then place it into a bucket of soapy water.
- Soak the egg mass for a few days to destroy the eggs.
- Dispose of the water responsibly.
There is one natural threat to gypsy moth control and that is a fungus (Entomophaga maimaiga), that is active during damp spring weather. If a dry spring occurs, gypsy moth infestations are more widespread because the fungus does not reproduce.