This infestation suddenly appeared on the ornamental pear tree we planted in the spring. I'm guessing it may be tent worms. If so, can we just pick it off? If not, does anyone know what it is and what to do about it?
Yes, tent caterpillar. Generally won't hurt the tree, just looks nasty. Don't see any in there, so they may have come and gone. The branch will most likely leaf out next year. If you can live with the tent, leave it be. You might be able to get some of it out with a long stick or broom.
Thank you. The leaves within it all seem brown and dried. If it won't spread or hurt the tree, I can leave it, but reaching it is not a problem--the tree isn't that tall (maybe 7 ft). Can they really come and go that fast? I could swear nothing was visible a few days ago.
They were probably there longer than you perceived. Rip the web out and don't worry.
Fall webworms are a favorite prey for birds, squirrels, and a variety of arthropods. Ripping the web up allows these predators access to the feast, but for a tree as small as that, don't hesitate to get after those caterpillars with fairly strong streams of water. They are voracious feeders.
Your tree will be fine but I wouldn't put up with too much feeding activity on such a young tree. In the future, you'll need to keep a close eye on this tree each summer. The Fall Webworm construcfs their webs towards the ends of branches.....and don't appear overnight. They just start out teensy.
The Eastern Tentworm is a common spring sight and most often is more a cosmetic problem then a real need for elimination problem. On rare occassion they may defoliate a tree, which will then releaf, but repeated defoliation can weaken a tree so it eventually will die.
At an early stage of life they are susceptible to the Bacillus thuringiensis - Kurstaki sprays and often another disease spreads through them, you will se the wee buggers hanging from a thread curled into a "C" shape if it is present.
These are cousins to the Fall Webworm which can be handled in the same way.
Here is a link that might be useful: About Eastern Tentworms