I'm pretty discouraged with the winter moths too. I've had them for five years now. After this past winter, one of my mature Maples is less infested than the last few years, but the other one is just as bad. They also drop off the trees and munch on anything they fall on. They make a real mess every spring.

I actually have a couple of large branches on one Maple that appear dead this year for the first time. So I wonder how much they can take from these pests.

One of my neighbors sprayed his tree for winter moths, and he is not organically minded, so I don't know what he used, but he decided the spraying wasn't doing any good at all.

It's interesting that we've talked about planting more trees to counter the effects of green house gasses and climate change, but so many trees are under attack from one thing or another, it feels like a losing battle.

I have had a horrible infestation of winter moth caterpillars this year. The past 2 years have not been bad, and I don't recall even seeing a winter moth last fall. So I'm doubly surprised by how bad this years infestation is. I have a maple right next to my patio - the lower half of the tree has nary a leaf. And I practically have to shovel caterpillar poop off my patio. It is disgusting.

I had read Claire's UMass posting, and had been on the look out for eggs so I could spray right before hatching. But I could not find eggs on my trees at all. Guess I wasn't looking in the right places or for the right things.

No advice. Just sharing.

I was unaware that different strains or brands would be more or less toxic to non-target caterpillars - I've just bought whatever was in stock at Mahoney's, or at the hardware store down the street.

My understanding was that the critters need to ingest the stuff, so spraying only the maples or blueberries or roses would not harm butterflies, since they don't eat those leaves. I'll go look for the extension service post.

I've had very good results with Bt in the past, but haven't sprayed it this year. The caterpillar droppings are an incredible nuisance, though, so maybe I'll go pick some up, after the rain moves on.

The only articles I found on line (on any .edu or .gov site, at least) about B.t. killing non-target species had to do with GMO crops that have B.t. genes. The pollen from those plants can be lethal to other insects.

That's a very different scenario from a homeowner spraying trees, so unless there's really something published - preferably not sponsored by Ortho! - I think I'll assume that B.t. is pretty safe when sprayed on trees.

I'm just wondering if it is effective, why it has to be repeated every year?

I have used Spinosad (Captain Jack's brand) instead of Bt. Spinosad is organic but is somewhat more harmful to other creatures before it dries. I have been careful to spray only in limited amounts, never on actively flowering trees, and in the evening when bees are not active. It is supposedly not harmful after it dries, and can be used on organic fruit trees/plants. I primarily use it on a cherry tree and rose bushes; I wouldn't use it on a large tree. I find it to be very effective--the leaves are virtually untouched this year. Unlike B.t. it does not need to be reapplied after rain, and works throughout the life stages of the caterpillars. B.t. only works when the caterpillars are very small, so it's probably too late this season in most cases.

I tried to buy B.t. this year in an effort to be more environmentally friendly, but my Mahoney's no longer carries it. I explained to the manager why I wanted it and he said he'd consider re-stocking next year.

prairiemoon, it has to be repeated each year because it just kills caterpillars that ingest it directly from leaves. It doesn't persist from year to year, and winter moths are so pervasive that even if you somehow killed all the caterpillars in your own yard and thus interrupted their reproduction (extremely difficult if you have tall trees--it would need to be professionally applied from a crane), they would just balloon in from other people's trees the next year.

If you are going to use BT, then I would use BT - K. See the article below. "Bacillus thuringiensis var.
kurstaki (Btk for short) is used to control caterpillar pests
such as gypsy moths."

Spinosad is more effective with later instars of the larvae, but as pointed out above it's toxic to bees. Once it dries, however, it's fine.

In a lecture last week, an entomologist from URI mentioned that UMass has developed a biological control that should be introduced soon. He predicted that in 10 years time Winter Moths will be no more of a problem than Gypsy Moths.

Steve

Here is a link that might be useful: commonly asked questions about Bacillus Thruringus

I used to have a terrible time with these things defoliating everything on my property but I really haven't seen much of them over the last two years. This year, there's absolutely no trace of them so far. It's nice to see all of my trees with full foliage.

lalala, so my decision to do nothing seems like the right thing to do. I can't see spraying a mature Maple that is only going to have to be sprayed every year. I couldn't even spray the entire tree, unless I hired someone with a bucket to get the top, which would be too expensive to contemplate. I guess I am just going to have to let nature take it's course and if I lose trees, I will grow more roses and vegetables and replace the trees when winter moths are history. :-)

For now, I make the best of it. Winter Moth season will be over soon. New foliage will emerge. The hose set on jet will take care of the driveway and pathways.

But tell me, why does a brown, plain, moth, that is only around in late fall have to take up residence, instead of Monarch butterflies or any number of beautiful creatures that start out as a caterpillar? :-)

Pixie Lou: "And I practically have to shovel caterpillar poop off my patio. It is disgusting." I think this is one of the worst products of these damned insects. It sticks to the cars we park under our trees and is actually impossible to remove unless it is scraped off with a metal instrument.

PrairieMoon: My understanding from the UMASS website is that it's sprayed every year because, as others have stated, it needs to be ingested by the larval stage of the insect. Each year it has to be reingested because the larvae that live on will reproduce. They're an invasive species that were transferred to Canada and the New England area from abroad (probably Europe).

Places like New Zealand have extremely strict biological controls on immigrants. I'm sure they'll not see the winter moth for a very long time. It's a shame that these pests were let onto the continent (maybe an egg was carried in on boots or tools) because there aren't enough natural predators to keep them in check. I'm hoping that URI and UMASS can work in conjunction to produce an environmentally friendly remedy.

I'm not holding my breath, Persimmons on a solution any time soon, I guess. I have seen the birds eating them. A couple of years I had flocks of starlings in the trees enjoying a feast, but not this year. The weather has thrown the timing all off too, so I don't know if that is why I haven't seen the starlings this year. Maybe they were here earlier and left. They don't really put a dent in the population though. There's just too many of them. I have a lot of robins around, and I know they eat a lot of worms, but I haven't noticed them show much interest in the winter moth caterpillars.

Oh, I just noticed that my Japanese Maple near the back door is completely free of winter moths this year. Nice! So the Maple in the northwest corner of the yard and the Japanese Maple in the Southeast part of the yard did better this year. But the Maple in the northeast part of the yard, was just as bad. Interestingly, we had a lot of wind this winter and spring when it was very cold and the wind was whipping down that south corridor where the Japanese Maple is and it always comes from through from that Northwest corner. I wonder if that had anything to do with it?

Here's the UMass information regarding the development of a natural predator for Winter Moth.

"Cyzenis albicans is a Tachinid fly that parasitizes winter moth; in fact, winter moth is the only insect that it attacks. This important parasitoid was introduced into Nova Scotia through the 1950âÂÂs for winter moth and is now the controlling factor for this serious pest. It was also released in the western United States for winter moth there and showed great success. Cyzenis has now been brought to Massachusetts and a small initial release was performed in May of 2005 in Plymouth County. Following the 2005 release, Cyzenis albicans was released in increasing numbers each year in the following Massachusetts towns: Wenham, MA (2006); Falmouth, MA (2007), Wellesley, Seekonk and Barnstable in 2008 and again in Wellesley in 2009. Several years of releases will be necessary before any measurable effects are seen. The number of release sites is limited each year to carefully selected locations and at least 1000 flies are released at each site to maximize the chance of successful establishment. Production of flies for release has been augmented by the development of mass rearing techniques in the laboratory for both the fly and its winter moth host. We have also increased our Cyzenis collection efforts in British Columbia. This work is being performed by Dr. Joseph ElkintonâÂÂs lab group at UMass, Amherst. It is made possible thanks to funding from the USDA Forest Service, USDA, APHIS, the Mass. Dept of Conservation and Recreation and the Massachusetts State Legislature."

Steve

Here is a link that might be useful: Winter Moth overview - UMass

Wow, in Seekonk? You wouldn't guess that it was the case... I just read Claire's Umass Ext. update and I think I'm too late to be bothered spraying things on my trees now that the moths are almost done feeding. Next year I will be sure to murder them all.