This section is from the book "Commercial Gardening Vol1", by John Weathers (the Editor). Also available from Amazon: Commercial Gardening, A Practical & Scientific Treatise For Market Gardeners.
These flies belong to the genus Chry-sopa, and, as may be seen from fig. 161 (1), derive their name from the delicate veining of their wings. The eyes are golden green, very large and conspicuous, with two long, slender feelers on the head. The female is about \ in. long and larger than the male. The larvae shown at 3 and 4, in fig. 161, are very voracious, and will devour large numbers of aphides, including American Blight, in a very short time, and will even attack caterpillars about 3/4 in. long. These hairy larvae develop from eggs that are laid singly on hair-like stalks in rows and clusters, as shown in fig. 161, at 2, these slender stalks often projecting about 1 in. from the surface of the leaves or branches to which they are attached. After the larvae have fully developed they change into pupae and reach the perfect-insect stage in about three weeks during the summer months. The later broods pupate during the winter months in cocoons, as shown at 5 and 6 in fig. 161, and become perfect in spring.