It's actually the "silken tent" of the Eastern Tent Caterpillar, which annually makes an appearance in certain trees in Oklahoma during mid-Spring. With the warm spring, this annual event is a few weeks ahead of schedule, as everything else in Tulsa lawns and landscapes have been in 2012. The insects produce their webbing in the crotch of a branch in certain trees, such as hawthorn, crabapple, cherry, plum, and a few other trees. The silken tent serves as protection for the caterpillars when they are not out foraging on the tree leaves. The caterpillars usually are not found in such numbers that they defoliate or harm an entire tree. They are not usually detrimental to a tree's health, however control may be desired to prevent the ragged look these insects will produce by their feeding, along with the unsightly webs.
The easiest and cheapest control is simply to take a stick and destroy the web found in the branches, along with the insects, assuming you can reach it. Insecticides can be applied, but it's very difficult to penetrate the web. We usually don't recommend spraying, since by the time you see the webs, any damage may have been done. At this point, the larvae are close to going into the pupae stage, and hatch into harmless moths. So just take a stick and wack them out of the tree and you should be fine. You may even try a high pressure stream of water from your hose to break up the web and knock the caterpillars out of their web. If there are just a few webs found in your trees, I would not be that concerned about it, since they will probably not significantly damage the tree. Just think of it as helping to feed the local neighborhood birds.
We do expect a bad year for insects and their problems this year, due to the very mild winter. So while the Eastern Tent Caterpillar is not one to get real excited about, their are other insects that will harm your ornamentals. For information on how to care for trees and shrubs in the landscape, visit our website.