Possibly Tent Caterpillar Nest or Fall Webworm Nest

Subject: Nest
Location: Southwestern Pennsylvania 18mi north of Pittsburgh
May 19, 2013 10:17 pm
Today I photographed and interesting cocoon like nest, with a bunch of something(maybe insects) inside.
I’ve never seen a nest like this in the trees. It may, for all I know, it may be a small, tent caterpillar’s nest.
But the ones I’ve always seen are much larger.
I didn’t dig into the nest to find out ’cause I didn’t want to intrude on the bugs. Any Ideas?
Signature: Rich

Nest might belong to Tent Caterpillars
Nest might belong to Tent Caterpillars

Dear Rich,
We agree with you that this might be the newly started nest of a recently hatched colony of Eastern Tent Caterpillars.  We will try to get a second opinion from Eric Eaton.  More information on the Eastern Tent Caterpillar can be found on BugGuide.  As an aside, we will be flying into Pittsburgh in a few weeks to visit family.

Possibly Tent Caterpillar Nest
Possibly Tent Caterpillar Nest

Eric Eaton provides another possibility
Tough call.  I’m thinking Fall Webworm, as they tend to make webs on the outer reaches of branches, whereas tent caterpillars build webs in the crotches of branches, often several “tents” to one tree, or in a series of trees close to each other.  Fall Webworm tends to have more isolated colonies.

Thank you so much for the return email.
Have a good trip and a great stay at, “Da Burgh”.
Thank you both again for the rapid response and ID.
Isn’t it a bit early for webber caterpillars to appear?
Richard Rich

Once we received Eric’s response, we pondered the time of year.  Tent Caterpillars already have established nests in the spring and Fall Webworms are most noticeable later in the season, but they do begin hatching earlier.  Your “nest” might be the beginning of what will become a substantial “web” later this year.

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