Brown Ambrosia Aphid
Uroleucon ambrosiea
(Macrosiphum ambrosias)
This crowded aphid colony is on Brittlebush (Encelia farinosa) near Tortilla Flat, Arizona, USA. March 2009. Look closely and you might see the aphid wasp on the leaf at lower left.
Aphididae -- Aphid Family
Most aphid species are pretty hard to recognize just by looking at them without a microscope together with extensive expertise. Mostly they look like greenish blobs! Brown Ambrosia Aphids occur in spring on various members of the sunflower family in the Sonoran Desert. They have a rich red-brown color. Some years they are scarce to absent and in other years huge populations develop only to be consumed in great quantity by predators such as lady bird beetles, syrphid flies, lacewings and minute parasitic wasps. For gardeners the best solution is to knock many off with a stream of water and allow the natural predators to do their work against the rest. Most plants can handle pretty high numbers of aphids for brief periods.
Canyon Ragweed (Ambrosia ambrosioides) and Triangle-leaf Bursage (Ambrosia deltoidea) frequently host populations of this aphid and their predators. Surprising for some people, lettuce is also in the sunflower family and may host this aphid. Many aphid species have alternate hosts - what this aphid does for the summer and fall months in the Sonoran Desert is not known.