help...tree is encased in a "spider web"

We have a large tree, over 50 ft. tall, in our yard. It has been very hot and dry here for several weeks....100+ heat index. The trees leaves have started turning brown, so I thought it might be needing water. Looking close at the tree, I found that almost all of the tree branches, from the smallest down to the trunk, are coverered with what looks like a very fine spider web. Also, many of the leaves have a white granular substance on them. It is killing the tree rapidly, but not by cutting off the sunlight, because the web is so thin, surely it is still getting enough light. Anyway, I could not see that it was encasing the leaves also. What is causing this? Sorry, I don't know what kind of ttree it is, but it is not an evergreen, and never has any fruit or blooms. No other trees in my area seem to have this, either. There are three other trees on my lot, and they are all fine.
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Tent caterpilliars usually only make tents in the crotches of trees and by this time of the year they have already pupated, emerged, and are near laying eggs. You may want to look up "Euonymus caterpilliar" which is a pest that is known to cover an entire plant with thier large webs. This is the right season for them as well. You may also have an incredible infestation of giant mutant alien spider mites.
Toad
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It sounds very much as if you have tent caterpillar -- check the webs just after sunset and see if they have lots of little caterpillars in them. A tree can generally survive one round of defoliation if it is gently cared for following removal of the infestation. In any case, treating a 50+' tree is not a DIY; call a tree specialist.
Chris Owens
Jim Caldwell wrote:

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On Sat, 9 Aug 2003 16:52:54 -0500, "Jim Caldwell"

If the webs are only on the branches and not the leaves, it is probably what I saw in Houston not long ago. I forget what the cause was (some insect, obviously), but more than one source I looked at said it is harmless and should not cause any alarm. Try looking around on the Houston Chronicle web site for more definitive answers.
Keith For more info about the International Society of Arboriculture, please visit http://www2.champaign.isa-arbor.com /. For consumer info about tree care, visit http://www2.champaign.isa-arbor.com/consumer/consumer.html
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