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: