August 30, 2020: Web Worm or Tent Caterpillar?

I guess it's caterpillar season.  Last week it was the Polyphemous moth, this week it's webworms.  You've probably noticed a lot of caterpillar nests in the trees this year.  Along  Route 25 in Plymouth just west of 93 there was a stretch where every tree was nearly defoliated, much worse than anything I've seen around the Lakes Region.  In our area I've seen plenty of nests and bare branches but only in small pockets, especially on fruit trees.

Fall Webworm nests (Hyphantria cunea).

Unfortunately, this includes blueberry bushes.

Not very enticing blueberry picking.

People have asked whether these are tent caterpillars or webworms.  It's easy to know the answer if you remember the full name of these two pests:  Eastern Tent Caterpillar and Fall Webworm.  The tent caterpillars come out in the spring and early summer, while as their name indicates, the webworms are prevalent in late summer and fall, so what we are seeing now is the webworm.  Another way to distinguish them is by their nests.  The webworm builds large loose nests that cover a large area of the tree and its leaves.

And though they look awful, the Webworm's arrival late in the season means that they don't usually do great harm to plants they infest because much of the work the leaves need to do has been performed at this point in the season.  Still, if a tree is highly defoliated it will be weakened enough that it may not survive if it has other assaults.  

In comparison, the tent caterpillar builds a tight nest in the fork of the host tree.

Eastern Tent Caterpillars  (Malacosoma americanum)

I've always thought their nests were to provide a deterrent from predators, but the tent caterpillar actually builds their nest to keep warm - it lets them emerge early in the spring before other insects can get to their favorite tree.  [Ref:  Sam Evans-Brown, Ask Sam, NHPR]  Likewise, on hot days they will hide in the shade of the web, coming out to feed at night when it's cooler.

Unlike the gypsy moth, both the tent caterpillar and webworm are native to New England, so they have predators that help keep their populations in check.

Another caterpillar I see now is a smaller, smooth worm hanging from the trees on long thread.  

Possibly the Oak Skeletonizer (Bucculatrix ainsliella)

I think this is the Oak Skeletonizer but I'm not sure.  I saw similar caterpillars earlier in the summer which were green and this one is more brown colored.

But the Oak Skeletonizer has two hatches each year with the second occurring in early fall.  

Now an update on the loons family.  We continue to have multiple visiting loons on the lake so the chicks have been keeping close to one parent and staying in the southern half of the lake, while the other parent provides guard duty, but I did see them once this week and they are getting big.

Harold and Betty with mom or dad.

They're also changing color from their brown fluff to the patterns of an adult loon.

Starting to look like a young adult.

It appears one is significantly larger than the other though it could just be an illusion.  

I want to close this week with a poem written by Meredith resident Susan Goodnough who wrote it one morning sitting at the docks on Meredith Bay.

"Loon-Time At The Lake"
By Susan Goodnough

Dawn is breaking,

And I'm on the docks alone,

No... not any more,

Two loons visit me,

They look at each other,

One dives,

The other follows,

I wonder,

Where will they surface?

But, they won't tell me,

Ahh... in the distance,

Three more, then four,

Yet, another three,

Stately, serene, and magnificent,

I watch with gratitude,

And enjoy the silence.