how can i destroy gypsy moth egg cases on our trees? #732075 - Ask Extension

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how can i destroy gypsy moth egg cases on our trees? #732075

Asked October 25, 2020, 2:16 PM EDT

how can i destroy gypsy moth egg cases on our trees? i have heard oil sprays work but do they need to be specifically formulated for this use?

Kent County Michigan

Expert Response

MID-OCTOBER—MID-APRIL: Destroy egg masses.

Destroy egg masses by spraying them with a horticultural oil labeled for gypsy moth egg masses (available at lawn and garden centers or online) or by scraping them off and killing them. Do not use motor oil, mineral oils, non-horticultural oils or others not labeled for gypsy moth. Spray the oil onto the egg mass until it is soaked. If you scrape off egg masses, be very careful not to harm the bark of the tree. You could do more damage than good that way. Use a knife or paint scraper to gently scrape all of the eggs into a jar. Eggs can be killed by soaking them in soapy water for 2 days before discarding them in the trash. Don’t just scrape egg masses onto the ground or try to crush them with your shoe as they will survive to hatch next spring. Any parts of the egg mass you are unable to scrape off can also hold surviving eggs.

Be sure you are using a horticultural oil if you go that route.  Online, there were a few that were premixed.  Hopefully you won't have to buy a large container of contentrate.  Read the directions.  One article says the temperature should be over 40.  Perhaps if it is colder, the oil won't stick to the surface. 

The scraping and soaking in soapy water is more time consuming but maybe easier. 

Look under deck/patio furniture... they can be in some interesting places.



Mary Kretschman Replied October 25, 2020, 4:45 PM EDT
Here another reference pdf (pages 8-9) that suggests microwaving the eggs! as a possibility.
They also state that horticultural oil is designed to penetrate the soft covering that the female deposits over the eggs.  :
ef-store.widencdn.net  Gypsy Moth and Management
Mary Kretschman Replied October 25, 2020, 4:53 PM EDT
Thanks mary
i saw this on-like too
what concerned me was that the body oils I saw on-like mentioned lots of insects but not gypsy moth egg cases... in fact, as in your post to me, the on-line stuff specifically notes using a oils designed with gypsy moths in mind... I’m concerned as we had it really bad this year and sort of bad last year... I am willing to really go after the cases this winter (we have at least 3-5 Acres infested) but don’t want to use the wrong oil... have you seen or heard of one designed for moth egg cases??
thanks a ton
dave
The Question Asker Replied October 25, 2020, 6:54 PM EDT
I cannot recommend a particular brand to you.  If you google horticultural oil you will get many brands.  It is may be hard to find them in the store at the moment but you can order online.  The labels mention killing caterpillars but the oil will smother the eggs in the masses.  Some are available in spray bottles, which is a limited amount, obviously, and a lot of them are in larger containers.   I think they will all smother the eggs. 
You may want to consider applying sticky bands around the trunks of trees when the caterpillars hatch and move up the trunk to feed, next summer.  I realize that you have a lot of trees.. perhaps specimens near your residence might be candidates.

There is a fungal pathogen which was introduced several years ago which will kill the caterpillars.  Its effectiveness is dependent on rainfall.  Hopefully, next summer, this pathogen will add to the caterpillars' demise

I conclude with this quote from an MSU article which recommends burning the eggs as a possibile method of doing them in.   It's very satisfying..  I didn't want to recommend this method until I located it, so here it is:

"Search for gypsy moth egg masses on trees, firewood and outdoor furniture. Scrape egg masses into a bucket or similar container filled with soapy water, or burn or bury the egg masses. Don’t leave the eggs or bits of egg mass on the ground – those eggs can often hatch the following spring."
Mary Kretschman Replied October 26, 2020, 10:21 AM EDT
thanks mary...
The Question Asker Replied October 26, 2020, 1:03 PM EDT
You're welcome.
Mary Kretschman Replied October 30, 2020, 7:59 AM EDT

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