Over the last few days I noticed a lot of chewed-up leaves on the
ground beneath our large 25 foot tree. Upon closer examination I
found the following larvae attached to the leaves, as well as some fly-
looking creatures (not sure if they're related to the larvae).

Can anyone identify the offending vermin? Should I be concerned about
this? What steps should I take to get rid of the infestation and save
the tree?

Pics at the following address:

http://picasaweb.google.com/jseemann/InfectedTree

Thanks!!
Jason