Ever had a neighbor with a pesky pet? Maybe there's a dog that leaves more than footprints, or an aggressive cat that intrudes onto your property and beats up your pet. But humans aren't the only species that cares for other animals. Believe it or not, some ants actually raise their own form of livestock!
What on earth could an ant herd and care for? The animal of choice is
one we usually consider a pest—those little aphids that attack our roses and
other plants! The ants raise them because the aphids produce something called
"honeydew", and the ants will literally milk them for this sweet treat. Like
any good animal owner, the ants will vigorously defend their livestock, so anything
that might eat the aphids, may just be attacked by the ants. So much for adding a few
ladybugs to the area! In this case you have to fight two species to stop the damage
caused by only one. 
Contributor: Kodi R. Jeffery, Centennial Museum, University of Texas at El Paso.
Desert Diary is a joint production of the Centennial Museum and KTEP National Public Radio at the University of Texas at El Paso.
Two aphids on a plant stem; at the lower right, an ant. After Lutz, 1921.