Deb, fascinating story about the cowbirds, oropendolas
and hornets. I had learned in Costa Rica that some wren
species (rufous-naped, I think) like to build their nests in
the same trees as wasp nests, the idea being that the
wasps deter certain types of predator, but parasitic flies
were not mentioned. I also had the pleasure of observing
a Montezuma oropendola colonial nest tree and loved
the wild and crazy sounds they made and the way they
swung upside down from their perches.

Oropenolas, blackbirds, grackles and cowbirds are
all members of the troupial family (icterids). Wonder if
that factors in to ability/willingness to host cowbird
young.

Chris Maack
Anchorage, AK
CMaack at compuserve.com