Winter is coming… and so are the moths

It’s mid November and we’ve had enough hard frosts to pretty much kill off nearly every insect, but there’s one remaining pest that’s about to hit us with its full fury. Now’s the time to take some steps to protect your trees and shrubs from this ravaging creature.

It’s the winter moth, an invasive species imported from Europe that can cause devastating damage to your plants. They first arrived in Nova Scotia over a half century ago and slowly migrated southward. They have hit much of New England hard, doing immense damage. They are particularly fond of trees that produce fruited blossoms, like apples, crabapples, pears, cherries, plums, and especially blueberry bushes. They also attack ash and maple trees — sometimes completely defoliating them — as well as other species of native trees.

Around the end of November they will emerge from the ground. The males – ugly grey moths, about 2 inches across – will flock in great droves to lights at night. That’s the signal that the entire population is active and reproducing. The females can’t fly; Instead  they climb up trees and lay their eggs by the tens of thousands.

Next spring — around April — the eggs will hatch, and the small green worms will burrow their way into fruit blossoms and destroy them. They will then move on to the leaves, and in many cases they will strip them bare. If you have winter moth larvae in your trees, you’ll no doubt have seen their “ballooning” migration — they attach themselves to thin, silk-like strands and billow down from trees by the hundreds. After about 6 weeks of heavy feeding, they burrow into the ground, waiting for the winter to arrive to start the process all over again.

The numbers are unbelievable. Scientists say up to 250,000 winter moth larva can hatch in a single tree. Sounds like a locust plague, and in some ways it is. They don’t have any native predators to speak of, so their numbers grow substantially each year as they spread to new territory. In my own experience, they hit our neighborhood like a freight train 2 years ago. They ate their way through many of our neighborhood trees. I have 5 large blueberry bushes that produced 40 quarts each year — until the winter moths arrived.  I haven’t gotten a single berry since then.

What to do

With numbers like this, it’s hard to put a big dent in their population. But you can protect your most cherished trees, such as flowering crabapples or fruit trees. Right now your goal is to stop the females from climbing up the trunk. There’s a few ways to do this.

One way is to get some sticky tree wrap. It’s available in many garden centers. It’s a paper wrap that goes around the trunk, with a sticky coating on the outside that creates a barrier that the moths get stuck on. It’s semi effective — you really need to monitor it, as it can get overwhelmed by the sheer number of climbing moths. They can also crawl underneath it if the bark surface is fairly bumpy — or they will lay their eggs further down the trunk. If you use sticky tree wrap, check on it daily and replace the band as needed.

You can also spray heavy-duty insecticides on the female moths while they are climbing. I’m not a big fan of this approach, as I like to stick with organic solutions. It also requires frequent spraying, and no doubt many moths will muscle through when you aren’t monitoring and spraying. It’s not an effective remedy.

I have a third solution that’s proven highly effective — get some chickens and let them do the dirty work for you. Chickens are a fantastic alternative to pesticides in general. They spend their entire day eating bugs. It’s what they are hardwired to do. Here’s an example — I have a flower crabtree in my yard that was devastated by winter moths. Two years ago they stripped it bare of all its flowers and most of its leaves. The next year I built a chicken run under it,  and the following spring the tree was full of flowers and leaves — and also quite robust from the other “gifts” the chickens laid at its roots.

This year I’ve extended a temporary chicken run around my blueberry bushes. The chickens are already busy digging around underneath them, no doubt finding a trove of winter moths. I look forward to seeing what kind of impact they have on the winter moth population.

In many towns in the local area, raising chickens in your yard is legal and the regulations are common sense. Unfortunately in the town I live in, the rules arechix far too restrictive — it’s too bad, as chickens can solve some of the environmental woes that our government officials spend tons of time and money trying to regulate. But that’s a topic for another day.

This time of year provides you with your first opportunity to fight against the winter moths. If you have them, you should take steps to knock back the adult population by preventing the females from getting up into your most prized trees. In the spring you can wage another campaign against their larva. We’ll talk about that in a few months.

John Macone operates a small organic farm in Amesbury, Mass.