Help identifying type of borers?

Question

We have a Quaking Aspen tree and it was badly infested with, what we think is, borers. We are not sure what specific kind and would like to know so that we can find a way to kill them.

They leave long, round, narrow tunnels, and they tunnel to the middle of the tree.

What kind of borers are they? Are they even borers?
Thanks.

Answer 1

.............photos of borers...............
http://www.ext.colostate.edu/pubs/insect/05530.html
.............Ask a Master Gardner........
http://www.colostate.edu/Depts/CoopExt/4DMG/Ask/aska.htm
..................Quaking Aspen.................
http://www.rook.org/earl/bwca/nature/trees/populustrem.html
Insects: Poplar Borer, Western Tent Caterpillar, leaf rollers, Leaf Miner Beetle, Roundheaded and Flathead Woodborer, all attack Aspen

http://search.yahoo.com/search?search=aspen+tree+borers&ei=UTF-8&fr=ks-ques&ico-yahoo-search-value=http%3A%2F%2Fsearch.yahoo.com%2Fsearch&ico-wikipedia-search-value=http%3A%2F%2Fen.wikipedia.org%2Fwiki%2FSpecial%3ASearch&p=aspen+tree+borers
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...........Treatment for the tree...........
http://www.coloradogardening.com/q&a_aspen.htm
Q:I live in Monument, Colorado. For the past couple of years my neighbor and I have noticed bores in our Aspen trees. The trees heavily sap at the site of the small little holes. Many holes can be found on a single tree, no matter what the age of the tree. What are these and how do we treat them? K. W., Monument, 5/25/06
A: The little holes in the aspen are the work of poplar borers. The adult is a grey beetle that can be found on aspen trees in summer. The greatest damage to the tree is caused by the larvae which tunnel into the tree and continue to tunnel within the tree. Insecticides, such as Sevin (Carbaryl) or Permethrin, applied to the trunk in summer can kill the exposed adults.