The aphidoids are a diverse, economically important, and interesting group of insects. They belong to the group of insects known as the Sternorrhyncha which include related insects such as scales, psyllids, and whiteflies. The term Sternorrhyncha refers to the location of the mouthparts. The mouthparts are found on the ventral side of the insect between the fore-coxae and project
backwards.
Although there is some debate within the scientific community, for the purposes of this website,
the Aphidoidea is comprised of three families: Aphididae, Phylloxeridae, and Adelgidae. This website concentrates primarily with the family Aphididae (aphids).
Aphidoids are small soft-bodied insects, ranging from 1-5 mm long and feed on plants. They are usually found living in colonies on their host plants. Aphids occur predominantly in the northern temperate regions of the world. The life cycle of these insects includes both parthenogenetic, or asexual, and sexual reproduction. This life cycle may also include production of eggs or living young depending upon the cycle.
Adults include winged (alate) or wingless (apterous) forms.
The antennae of these insects are usually 6-segmented with the last segment modified into a narrowed projection called the terminal process or unguis. Most aphids have two-segmented tarsi, the second segment bearing two claws. Aphids usually have two prominent structures on the posterior dorsum of the abdomen called cornicles or siphunculi. In some species, these structures are reduced to mere pores. Another structure unique to the aphids is a posterior projection on the tip of the abdomen called the cauda.
Selected References
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