Spongy Caterpillars Again Laying Waste To Swaths Of Vermont Forest

A gloomy January day or mid-June. This is part of 
Colchester, Vermont where trees are under siege
from the defoliating spongy caterpillars.

 As I'm sure many of you have noticed, large sections of Vermont woods are defoliated for the second year in a row by those awful spongy caterpillars. 

The name of these caterpillars might not be familiar to you, but the destruction sure is.  Until recently, these awful bugs had a name that was a slur agains the Roma ethnic group. 

We had the same problem last summer, of course. Eventually, a fungus that kills these things helps ease the outbreaks. But apparently, this spring wasn't wet enough to make the fungus thrive, so the caterpillars did instead. 

Some places, like parts of Chittenden and western Rutland counties, are getting hit for the second year in a row. Other places, like much of Franklin County, don't have it as bad as they did last year.

Most trees survive these defoliations, even if they hit two years in a row. At least as long as the trees can put out some new leaves in the second half of summer, once the caterpillars stop eating.

I did notice, though, that this spring, the defoliation in some places started as soon as the trees began leafing out. Last year, most affected trees had leaves into at least early June which helped them withstand the onslaught a little better. 

I do think we will see dead trees in the hardest hit areas of Vermont after this second season of the scourge. Sure, most of the affected trees will live, but not all of them.

In the hardest hit areas, like in parts of Colchester, it looks like the dead of winter the defoliation is so complete.

Although this situation isn't widespread enough to noticeably affect the weather overall in Vermont, the areas that got really nailed by the caterpillars are probably seeing their local conditions affected and will continue to see that unless or until the leaves come back.  

Summer days will be hotter in these defoliated zones, since the sun is baking the ground. Leaves are no longer in place to provide shade. so the heated ground will in turn heat the air. Also. leaves have a cooling and cleansing effect on the environment. That's gone, so the heat is on.

If we have any dry spells, the defoliation can contribute to highly local droughts. The ground dries out much faster in areas with no foliage.  The lack of foliage also heightens the risk of small brush fires since leaf litter and branches and stuff  get super dry super fast without leaves overhead. 

The biggest negative effect is probably psychological. We still have our long winters here in Vermont, so we look forward to the lush green, leafy landscape of the relatively short summers. The spongy caterpillars are taking that away from at least some of us. 

It's unclear how many more years of this we have to go through before the spongy caterpillar boom finally ends. We can hope for a wetter, foggier, cloudier and more damp spring next year to encourage that fungus. 

Video:

Extensive defoliation of trees in Colchester, Vermont last week.  If you don't see the image for the video in this post, click on this link to view:

Another Vermont Drought Bummer: Very Hungry Caterpillars Defoliating Forests

A large patch of defoliated trees on a hill near my 
house in St Albans, Vermont. Gypsy moth caterpillars
are laying waste to stretches of forest in the state
this year. Dry weather is partly to blame for 'the
resurgence of this pest.

 Especially if you're in the Champlain Valley, you've probably noticed it.

Big patches of normally green hillsides are brown and leafless. Or, if you're particularly unlucky, the trees in your yard are getting devoured and caterpillars are pooping all over you if you step outside.  

They're gypsy moth caterpillars, and they're causing the biggest defoliation in Vermont since 1991.

The dry weather this year is largely to blame. So yeah, another problem created by drought or near-drought. 

A happy fungus took hold in Vermont in the early 1990s that goes after gypsy moth caterpillars, keeping them in check. If you have a succession of soggy springs and early summers, you still get those little hungry buggers, but they are reduced and number and the trees and forests stay more or less intact. 

Recent springs have been dry,  especially last year and this year, so the very hungry caterpillars have come roaring back.  

Sure, it rained early this week, which is nice, but that's far too late and too little to do much to encourage that wonderful caterpillar-killing fungus.  (The quarter inch of rain that fell on St. Albans yesterday was less than in other parts of Vermont, helping cement my town as part of the Great Champlain Valley desert).

Even worse, now that the caterpillars are back with a vengeance, they might stick around for a few years. Lots of wet weather this summer and especially next spring and the spring after that would help a lot. 

I know we like bright, sunny spring weather, but I hope spring, 2022 is just one long slog of foggy, drizzly days. 

I've got selfish reasons for that. There's a big patch of defoliated trees on the hill above my house, and it's creeping closer to my property. 

The trees around my house give me a great deal of privacy in the summer, which I love. Plus, some of the trees aren't the healthiest.

Most healthier trees can survive a season or two of defoliation, but ones that already have pre-existing issues often do not. Newly planted trees are also in danger. 

We sure picked the wrong summer to spend lots and lots of cash to plant a nice big river birch in our St Albans yard to replace the willow that blew over in a storm a couple years ago.  Despite lots of watering, it's suffering from the dry weather, and gypsy moth caterpillars love munching on river birch. Sigh. 

The gypsy moth caterpillars will wrap up their destruction  later this summer, but who knows how many years this problem will last before that wonderful fungus can gain the upper hand?

It's not just us having this problem, by the way. Parts of Ontario, Quebec, Wisconsin and New York, among other places, are having a battle royale with the caterpillars. 

If you have some prized trees, there are only a few things you can do about the problem. You can wrap burlap around the base of trees so egg masses are laid there instead of in the tree.  Then later on, you can remove the burlap and destroy the egg masses. Putting caterpillars and their egg masses into soapy water kills them. 

Experts say the Great Vermont Gypsy Moth Caterpillar Munchathon will continue for about another month before it wanes.  Those buggers will turn into moths, then regroup to torture us next year.