Life-history of Scale Insects.— In an excellent account of the 

 Scale Insects affecting deciduous fruit trees Mr. L. O. Howard dis- 

 cusses* the life-history of the Coccida? as follows : In respect to life history, 

 the family Coccidse, which includes all of the so-called scale insects, is 

 very abnormal. The eggs are laid by the adult female either immediately 

 beneath her own body or at its posterior extremity. Certain species 

 do not lay eggs, but give birth to living young, as do the plant lice. 

 This abnormal habit is not characteristic of any particular group of 

 forms, but is found with individual species in one or more genera. The 

 young on hatching from the eggs are active, six-legged, mite-like 

 creatures which crawl rapidly away from the body of the mother, 

 wander out upon the new and tender growth of the tree, and there 

 settle, pushing their beaks through the outer tissue of the leaf or twig 

 and feeding upon the sap. Even in this early stage the male insect can 

 be distinguished from the female by certain differences in structure. 

 As a general thing, the female casts its skin from three to five times 

 before reaching the adult condition and beginning to lay eggs or give 

 birth to young. With each successive molt the insect increases in size 

 and becomes usually more convex in form. Its legs and antennae be- 

 come proportionately reduced, and its eyes become smaller and are 

 finally lost. As a general thing, it is incapable of moving itself from 

 the spot where it has fixed itself after the second molt, although certain 

 species crawl throughout life. The adult female insect, then, is a 

 motionless, degraded, wingless, and, for all practical purposes, legless 

 and eyeless creature. In the armored scales she is absolutely legless 

 and eyeless. The mouth parts, through which she derives nourishment, 

 remain functional, and have enlarged from molt to molt. Her body 

 becomes swollen with eggs or young, and as soon as these are laid or 

 born she dies. 



The life of the male differs radically from that of the female. Up to 

 the second molt the life history is practically parallel in both sexes, but 

 after this period the male larva transforms to a pupa, in which the 

 organs of the perfectly developed, fledged insect become apparent. This 

 change may be undergone within a cocoon or under a male scale. The 

 adult male, which emerges from the pupa at about the time when the 

 female becomes full grown, is an active and rather highly organized 

 creature, with two broad, functional wings and long, vibrating antenna?. 



* Yearbook U. S. Dept. Agr., 1894. 



