As of 2022, spongy moth is the new common name for Lymantria dispar dispar, previously known as European gypsy moth, EGM or LDD moth. 

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In 2020, Ontario suffered a major gypsy moth infestation, starting in Southern Ontario and spreading from Niagara to eventuall reach Estern Ontario.   Major damage was widespread, including at Sharbot Lake, Kaladar, Bob's Lake/Crow Lake, Otty Lake, and Mississippi Lake.    

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Having established itself in our area, there is risk of another infestation should conditions become favourable.  A Gypsy Moth infestation can create sever defoliation of all oaks and basswood, while also feeding on balsam fire, hemlock, elm, poplar, cottonwood and birch . (Source: Forest Health Tech MNRF).  

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Some Facts

 

• The larvae (caterpillars) feed on foliage of a wide range of hardwood and some softwood trees.

• The gypsy moth has over 300 known host plant species with oak, maple, birch, alder and hawthorn being some of their favourites.

• Defoliation of the tree canopy in many areas across Ontario was widely observed in 2020

• Gypsy moth is most destructive in its larval stage. A single caterpillar can eat an average of one square metre of leaf material over its life span

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Effect on Area Trees

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• Hardwood trees may try to re-foliate, but this puts stress on their resources, especially when drought-like conditions exist. Trees may suffer longer term consequences such as crown die-back or even death. 

• Trees which were already weakened after three years of defoliation by Forest Tent caterpillar may be more susceptible.

• Conifer trees may suffer more immediate consequences of defoliation, and may die within a year if all needles have been stripped from the trees.

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What You Can Do

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• At first sign of caterpillers, band your trees with burlap. Wrap a piece of burlap cloth around the trunk of the tree, tie a piece of twine around the centre of the burlap and drape the burlap cloth over the twine so there is room for the caterpillars and adult moths to take refuge during the day

• Check the trap and remove and transfer the insects to soapy water for a few days and then dispose.

• If you find pupating insects, place them in soapy water and dispose.

• Look for egg masses. These eggs are left to overwinter and hatch in the following spring. Scrape the masses off the tree using a putty knife, butter knife or a paint scraper and place in soapy water for two days, then  dispose.

• Water your trees if you are not under water restrictions.

• Protect the root zones of your trees.

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Plan for Next Year

 

Ahead of warm weather and a new hatching season, consider spraying trees with hand-held sprayers using Bacillus Thuringiensis Kustaki (BTK). This kills the caterpillars and is non-toxic to humans, pets, birds, fish and other insects.  BTK is recommended, but will require multiple treatments during the feeding phase.

 

Working together

 

Consider contracting with service providers who may have larger equipment that can reach higher into the canopy of trees. Organize with neighbours or landowner associations to conduct aerial spraying of BTK.  If this option is being considered, planning for the next year's season required plenty of lead time as there are many logistical challenges including:

• can you find a suitable spray contractor?

• can you ensure a supply of the BTK product?

• do you have a large woodlot of your own, or can you enlist enough neighbours to ensure that the spray blocks are of sufficient size for aerial spray operations to be practical and effective?

• does your town council or municipality have a plan?

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