Order:
Family:  Dactylopiidae
Diet:  Cacti.
Vegetation Association:  Can be seen on cacti underneath the white fluffy material.  This white material they secrete from abdominal glands. 
Predators:  Ladybird beetle, small moths in the caterpillar stage.
Life Stages:  Incomplete metamorphosis; egg, nymph, adult. 
Notes:  Have been ground up and used by native peoples to dye textiles red or purple. This is an aphid.

Photo: Taken at Jewel of the Creek at Cave Creek on September 29, 2007. The bugs are the white blotches on the prickly-pear cactus. For more photos, click on camera icon.