Aphis \A"phis\, n.; pl. Aphides. [NL.]

(Zo["o]l.) A genus of insects belonging to the order Hemiptera and family Aphid[ae], including numerous species known as plant lice and green flies.

Note: Besides the true males and females, there is a race of wingless asexual individuals which have the power of producing living young in rapid succession, and these in turn may produce others of the same kind for several generations, before sexual individuals appear. They suck the sap of plants by means of a tubular proboscis, and owing to the wonderful rapidity of their reproduction become very destructive to vegetation. Many of the Aphid[ae] excrete honeydew from two tubes near the end of the body.

Source: Webster's Revised Unabridged Dictionary (1913)