3 keys to battling your winter moth infestation

If you noticed ugly grey moths flitting around your property in late November and early December, I have some bad news for you — you have a serious bug problem that will erupt in about a month.

But there are some things you can do about it, and that’s what we’ll talk about in this week’s blog.

Those bugs were winter moths, a European invasive species that has been steadily chewing its way through the Northeast United States and Eastern Canada. Their offspring hatch as tiny green worms in April, and they’ll emerge by the millions — as many as 250,000 in a single large tree.

Here are some telltale signs that you have a winter moth infestation:

  • Lots of moths flying around your property at night in late November/early December.
  • Dozens (or hundreds) of tiny lime-green worms hanging from silk-like strands in April and May.
  • Cars and outdoor furniture covered with tiny black pellets in April/May (this, I hate to say, is their poop).
  • Leaves on your maple, ash, and flowering trees chewed heavily, if not completely denuded.
  • No fruits on your fruit trees and blueberry bushes.

They love to eat all sorts of flowering trees and bushes — crabapples, apples, plums, cherries, and blueberries, to name a few (they don’t seem to like peaches or raspberries…hmmm…). They also eat the leaves of maples, ash, and many other hardwood species of native trees. They’ll wipe out the buds on these trees and bushes when they are most vulnerable — when the buds are swelling and starting to blossom. They will wipe out your fruit crops and do serious, potentially deadly, damage to your trees.

This is the time of year when you can start to fight back. They’ve laid their eggs in the bark of your trees, and so they are somewhat vulnerable. Winter moths don’t have a natural predator here in North America to keep them in check, so it’s crucial to take steps to reduce their numbers.

There’s a two=phase strategy you should employ.

Phase 1 –Dormant oil sprays and insecticidal soap

Before your trees start to break open their buds, you can apply sprays that will kill at least some of the eggs that winter moths have laid on the bark.

Spraying your trees isn’t as much of a hassle as it sounds — as long as they are fairly small trees, like no taller than 10-15 feet. If they are taller than that, I’m afraid they’re a lost cause (but there’s some hope — see Phase 3).

You can buy a 2-gallon spray can for about $20, and the  ingredients for dormant oil and insecticidal soap compounds are cheap and easy to come by.

Here are a few recipes:

RECIPE 1: 2 tablespoons of ultrafine canola oil and 1 tablespoon of baking soda mixed with a gallon of water.

RECIPE 2: 2 tablespoons of horticultural oil, 1 tablespoon of baking soda, 1 tablespoon of kelp and 1 tablespoon of mild dish soap mixed with 1 gallon of water.

RECIPE 3: 2 tablespoons of baking soda, 5 tablespoons of hydrogen peroxide, 2 tablespoons of castile soap and 1 gallon of water.

You should apply the spray when the trees are dry, and the temperature is above freezing. These sprays can potentially do some damage to the tree itself, so you need to be careful.

These sprays will apply a thin film that will suffocate the eggs, but I’ve found they aren’t terribly effective on their own. Winter moths are clever at laying eggs in crevices and nooks that make it hard to get a solid dose of spray on them. Still, you’ll  put a dent in the population, and that’s good.

Phase 2 — Organic bacteria spray

Once your trees start to bud out, you need to change your strategy. The winter moth larva hatch and start to crawl to buds to begin their feeding. They are voracious, so you need to pin their ears back by applying some generous sprayings of an organic insecticide called b.t. kurstaki. A quart of it will cost you about $15 to $20, and that’s enough to apply about 20 sprayings to your trees and blueberry bushes. You’ll want to spray about every 3-4 days from around mid April to mid May.

B.t. does a number on the moth larva’s digestive system. It will kill them in large numbers if you are diligent and thorough with your spray applications. This is your best and last option for spray controlling them — once they begin to mature the b.t. is ineffective.

Phase 3 — The poultry option

Nature always seems to provide remedies to balance things out, and in the case of winter moths there is a bonafide natural solution. It’s backyard chickens. They eat just about every bug you can imagine, including some species that pose serious health problems to humans such as deer ticks that carry Lyme disease. Chickens will plow through a big population of winter moths and will utterly devastate it, as long as they have access to the ground underneath the tree or bush.

Chickens are a natural, low-cost and low-impact solution to many bug problems that we currently use expensive and environmentally-damaging pesticides to deal with.  Some communities have progressive laws regarding backyard chickens that allow homeowners the flexibility to own small flocks. Unfortunately, my hometown of Amesbury isn’t one of them. Most people here are prohibited from having chickens due to the size of their lots. And even those who have large enough lots must adhere to onerous regulations. These laws can be changed, but for now, most Amesbury residents need to spray and pray in order to knock back the winter moths.

John Macone operates Farmer John’s Organic Foods, a neighborhood organic farm in Amesbury. Add https://www.facebook.com/Farmerjohnsfoods/ to your list of Facebook likes to keep up to date on fruits, vegetables, plants and fresh eggs that are sold at the farm.


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