Tree Killers: Spongy Moth

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  • Common English name: Spongy Moth
  • Other names: LDD moth
  • Latin (scientific) name: Lymantria dispar
  • Important Note: The invasive moth species Lymantria dispar dispar (LDD) was previously referred to as the European gypsy moth, and is no longer in professional use.

Threat type

150x150 insects

History in Canada

  • introduced from Europe to North America (Massachusetts) in 1869 for possible silk production
  • now well-established in the eastern US as well as small populations in western US
  • in Canada, it is most abundant in Ontario and Quebec
  • also occurs in small numbers in New Brunswick, Nova Scotia, and British Columbia
  • in BC, aggressive monitoring and control have prevented the moth from becoming established but introductions of egg masses from the east occur regularly


  • the female moth is mostly creamy-white with some dark markings and a wingspread of up to 62 mm (2 ½ in)
  • the male is darker and smaller with a wingspan of 37-50 mm (1 ½-2 in)
  • the female cannot fly so lays a single egg mass close to where she has emerged after pupation
  • each egg mass contains up to 1500 eggs
  • egg masses are laid on trees, rocks, or manmade objects, such as tires, trailers, or firewood
  • the species is easily spread when these objects are moved prior to the eggs hatching
  • eggs hatch in early spring and the caterpillars feed until mid-summer
  • the caterpillars are hairy with two rows of large spots on the back: red spots at the head end and blue spots at the tail end
  • caterpillars grow to 60 mm long (2 ½ in) when mature
  • Gypsy moths have one brood per year and overwinter as eggs
  • populations tend to cycle over the course of several years, going from abundant to rare and back

Impact on Trees

  • larvae can eat over 500 species of trees and shrubs but prefer oaks and poplar
  • trees can be completely defoliated when larvae populations are high
  • several years of defoliation can kill a tree

What can be done to control this tree killer?

  • in BC, an aggressive program of trapping adults and spraying trees with a biological insecticide (Btk) in areas where the moth has been found has prevented establishment
  • aerial and ground-based spraying of Btk as well as chemical insecticides to kill the larvae have been used in eastern Canada
  • there are several parasites and birds that attack the larvae

Photo Gallery:

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