Acrobat Ant
Crematogaster spp.
Observed at Mesquite Wash, Maricopa Co., Arizona, USA. March 2008. The ants are attending to small green aphids on new spring growth of Goodding's Willow (Salix gooddingii). The species shown here could be C hespera.
Formicidae -- Ant Family
These distinctive ants can be readily identified to genus by their small size (ca. 2mm) and the spade-shaped abdomen. They move slowly and very often visit or tend to aphids or scale insects. There is a stinger at the abdomen tip - too small to penetrate human skin - but effective at repelling small predators, including those that might harm the aphids. In return for their protection, the aphids secrete sugary honeydew for the ants.
In the Sonoran Desert, these ants also visit extrafloral nectaries and exudates from developing flower buds - especially cacti. Here again, the ants offer some protection by virtue of their pugnaceous little sting.