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Female spongy moth laying eggs

Female spongy moth laying eggs

spongy moth egg mass

Spongy moth egg mass

What should you be doing?

This has been another year of significantly high Lymantria dispar, or spongy moth (formerly “gypsy moth”) populations across much of Pennsylvania. What should you be doing this time of year?

Help Defoliation of Trees

The spongy moth life cycle is about complete, we are past the point of peak defoliation and trees are trying to push out new leaves. The caterpillars have pupated and turned into moths. Most of the female moths have laid eggs or are in the process. Once egg laying is complete the moths will die. Spongy moths overwinter in the egg stage. There is only one generation of caterpillars per year.

Healthy trees can typically survive a single defoliation. Defoliation does stress the trees, making them more susceptible to other insects or diseases. Add to that other stress factors such as drought, soil compaction, etc. and the trees may die.

Reduce spongy moth populations

To reduce spongy moth populations for next year, egg masses can be destroyed by spraying them with a horticultural oil labeled for spongy moth egg masses. The oil needs to be sprayed onto the egg mass until it is soaked. It is not recommended to use motor oil, mineral oils, non-horticultural oils, or others not labeled for spongy moths.

Eggs can also be eliminated by scraping them into a container of soapy water and allowing them to soak for two days before discarding them. When scraping, be careful not to harm the tree. Scraping the egg masses onto the ground does not work and the eggs will likely still hatch next spring.

Best time of the year to spray

Many egg masses will be out of your reach and unable to be sprayed or scraped. If a high number of egg masses remain on your tree(s) it is likely you will experience another year of defoliation next summer. Therefore, it is best to have your trees sprayed in the spring once the caterpillars have emerged. To be most effective, the insecticide used to control spongy moth caterpillars must be applied when they are in their early stages of growth.

Professional Assessment

To have your tree assessed for spongy moth, contact Cutting Edge Tree Professionals. An Arborist Representative will visit your site and provide a free estimate to have your trees treated next spring. Call now at 814-201-9757 so we can be sure to get you on the calendar!

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