Gypsy Moths

[jb616]

I have seen posts from previous years but thought I would throw this out there. I seem to have a Gypsy Moth infestation on my 40 acres this year and some of the Oaks are about 50% defoliated. I have heard that they will attack Beech and Maple as well which I have both. What can a guy do to stop this without going broke or crazy? Can I do something this year, or wait til Spring?  Thanks in advance for your advice, I have approximately 200-300 Red, black, and white Oak, primarily Red. 

[Crusarius]

I am in the same boat. I am hoping its cyclic and they go away before they kill my trees. But I really look forward to any info on this topic.

[Wudman]

I am not an expert on the subject, so someone with more knowledge may provide better information.  First off, I would report it to your respective state forestry departments.  If the event is widespread, it may be on their radar screen for some type of control.  There have been attempts through the years at a landscape treatment using BT (Bacillus thuringiensis).  It is a naturally occurring microorganism that is toxic to gypsy moth larvae (and some other caterpillars as well).  It is applied as an aerial spray.  I doubt it would be cost effective to attempt it on your own.  

For individual trees, you could treat them systemically with imidacloprid if registered for such use in your area.  Imidacloprid is an insecticide that can translocate through the roots to the stems and leaves and provide some protection.  I have seen it used to protect individual high value trees from Emerald Ash Borer.  It is also used in flea and tick prevention for dogs.  I use it for that purpose.  It is good stuff, but comes with a price tag.

Finally, most folks do nothing for gypsy moth.  You have cyclical ebbs and flows in the population.  They are there one year and less prevalent the next.  Trees are normally able to withstand an occasional defoliation. Unfortunately, we have a lot of secondary pests in this country now and some other pathogen may grab a foothold when trees are stressed.  Weather patterns are somewhat unpredictable and trees may succumb to drought stress or other stressors following defoliation.  I hope things work out for you.

Wudman

[Crusarius]

Thanks wudman, I figured it was cyclical and wouldn't last that long. Just hoping my trees can survive. I just had 3 real nice oaks that suddenly lost almost all of their leaves this year. Doubt those will come back.

[Ron Wenrich]

I chased the moth when it was in PA back in the late '70s and early '80s.  We had massive defoliation.  Primary species hit was oak.  We don't have too much beech or hard maple in my area.  I don't recall as much damage to the soft maple or black birch.  Those were more scattered through the woodlots, and more in the lower diameter range.

You won't get too much mortality from a single defoliation.  It takes several years to amass large scale mortality.  3 years was usually the worst, as at that time the population is at its largest extent.  What happens next is the population collapses.  With the population collapse, there usually aren't any large scale defoliations again.

My experience back then was that black oak was hit the hardest, followed by chestnut oak, then red oak.  We don't have a huge amount of white oak in my local stands.  One factor that seemed evident were the dominants were best equipped to survive.  They had the best crown and were often the biggest trees in the woodlot.  Co-dominants were ones that were hit pretty hard.  Suppressed trees were often an off specie and not very abundant.  We found that on some sites, 80% mortality in some oaks happened.  In my area, site changes as you move up the ridge, and normally better on north sides.  Dry sites were often hit harder.  Sites with a stand density to promote tree health was often better than those that had heavy stocking levels.  

Since the '80s, PA hasn't had too many instances of outbreaks.  During the height of the moth infestation, the State did very little spraying.  It was only carried out only around residential areas, and only on the borders.  If you spray and your neighbor doesn't, you'll have gypsy moth the next year.  The state did develop a parasitic wasp that eats the larvae.  You'll see little holes in the egg masses when they're active.  

At the time, the management practice was to let the moth have their way and then salvage what timber that was dead, and to start managing with the trees that survived.  Some areas were clearcut due to the heavy mortality.  But, most were thinned out.  

[jb616]

I did contact the Conservation District Forester and the county is not going to do any spraying. He did say that I could scrape egg sacs off the trees and soak them in soapy water. An article that I read stated not to remove the egg sacs but spray them with a mineral oil spray so I am not sure which would be more effective. He did state that if they do get into the White Pine that they may not survive because they will not refoliate. 

[Crusarius]

I used a map gas torch  They pop like popcorn.

[Ron Wenrich]

I don't recall gypsy moth being a problem with any of the pines.  

I was always told that you can only see about 10% of the egg masses.  I found them in rock crevices, under fallen branches, and under branches farther up the tree.  Trying to control the moth with any mechanical means is pretty much a waste of time.  There's a lot more of them than there is of you.  

If you want to protect some yard trees, I think there is some injectable insecticides that would probably take care of them.  But, it isn't a cheap way to go.

[Jeff]

If they run out of oak they will eat maple and aspen and will eat white pine. I had a nice pine I lost here in the late 80s. They defoliate a whitepine and it is done.   Most of Harrison and much of clare county looks like winter this year. My place isnt as bad, but I have been pro-active for 3 years removing egg masses and killing caterpillars. You only have to go to the other end of my road to see the bare trees. The local conservation district is worthless. I've been beating the drum here for those 3 years warning what was coming. Enough of the important people this year were effected (infected) that there will most likely be a renewal of a bt spraying millage. People had to stay home this year and being outside was like being in a word that sounds like split storm.

[BradMarks]

Aerial spraying of  BT was very common here years ago. All the community and surrounding area into the woods. I believe the Gypsy Moth attacks firs also.

[BaldBob]

@Bradmarks, I believe the spraying of BT in Oregon years ago was for Douglas-fir Tussock moth and Western Spruce Budworm. At least that's what it was for in the Blue Mts. when I was managing timber there. I am unaware of significant Gypsy Moth presence in Oregon.

[BradMarks]

Lane County area where I live had 350 sq. miles sprayed in the early 80's with BT for the gypsy moth. My bad if I included fir trees as a target. It was almost 40 yrs ago ;D

[ESFted]

Back in the early 60's I worked summers between semesters as an Agricultural Research Service plant pest control specialist.  Set paper traps coated in tanglefoot and baited with female gypsy moth hormone in a half mile grid covering a couple of counties in upstate NY near the St Lawrence.  One day my boss tracked me down to the dentist office where I was having a filling done and congratulated me on catching the first ever Gypsy Moth in the state. Couple of years later they had overrun the Hudson River valley like a swarm of locusts.

[chestnut]

 Back in 99 my brother and I was working on a cabin in the mountains of Mifflin county Pa.  The forest here is predominantly oak and the Gypsy moth were so bad that the falling 6!@#%^&* sounded like rain.  Then it started to rain more than normal and it killed most of the caterpillars. I heard that the wet weather caused a fungus to grow and that's what killed them. It actually stunk in the woods for a while. The dead caterpillars were hanging from the bark and they looked like a tear drop of goo. 

P.S  don't hit one with a hammer. Makes a mess on your shirt. ;D

[BaldBob]

@Bradmarks, After doing some research, I see that Gypsy Moth is a problem in the Willamette Valley and they are still spraying BT almost every year in lesser or greater amounts. Fortunately population levels are at a point where they still refer to eradication  rather than just control ( maybe overly optimistic). We used a lot of BT in the 70's & 80's in the Blue Mts., but it was for Douglas-fir Tussock moth and Western Spruce Budworm.  There was one Gypsy Moth trapped in the Bend area last year, but they are pretty much absent East of the Cascades in OR & WA. I hadn't realized we had Gypsy Moth out here until you piqued my curiosity.

[Crusarius]

yes. this infestation was the raining from the trees poop. I have never experienced it before now. Pretty disgusting.