The Spongy moth (which is formerly known as the European Gypsy moth) is a non-native moth species that can wreak havoc on healthy trees found all over Eastern North America. In high populations the Spongy moth, in its caterpillar stage, can defoliate trees in a very short amount of time. Repeated years of tree defoliation can be deadly to trees.
The Life Cycle of the Spongy moth
Spongy moths go through 4 development stages:
- Egg stage - Late August to early May - a good time to inspect and destroy
- Caterpillar stage - Early May to mid-July - apply a biological insecticide
- Cocoon/Pupae Stage - Early to mid-July - can be removed by hand
- Moth stage - around mid-July to mid-August - The shortest stage , focus on other stages 1-3 above.
Photo: Spongy moth cocoons after pupae emergence
About the female Spongy moth
Mainly white in colour, the female Spongy moth has a wingspan of 60 - 70mm with dark brown zig zag lines that cross horizontally across their wings. Female Spongy moths remain on the tree they fed on while in the caterpillar stage. Their body mass makes it difficult for them to fly.
About the male Spongy moth
The male moth is brown in colour with darker brown zig zagging lines horizontally across their wings. The male moth is smaller than the female and has a wingspan of 35 - 40mm. Only male moths can fly.
Adult moths have a very short lifespan of about two weeks. They do not eat during this time. Their sole purpose during these two weeks is to reproduce and lay eggs.
Which trees are affected by Spongy moths?
Spongy moths prefer leaves from deciduous hardwood trees such as oak, elm, poplar, birch, willow and maple trees. They may also defoliate softwood trees such as blue spruce and white pine.
What are the first signs that I may have Spongy moths?
Learning to recognize the Spongy moth egg mass is important. Eggs can appear as fuzzy tan or cream coloured masses, about 1-2cm in width and 2-4cm long. There are approximately 100 -1000 eggs in each mass. These masses can appear on trees, furniture, woodpiles and buildings. If you spot any of these egg masses, remove by gently scraping them off. Destroy immediately by soaking them in a soapy water solution. Try your best to ensure that every part of the egg mass is removed.
Photo: Spongy moth egg mass, if left, this mass will hatch in May
Spongy moth Infestations
Severe infestations occur approximately every 5 - 10 years. These infestations can be devastating and rather quick. One caterpillar has the ability to consume one square metre of leaves in a single season.
What can I do to protect my trees?
Homeowners can protect their trees by using moth traps which use a pheromone to lure Spongy moths and eventually trap them.
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