34^ CONNECTICUT GEOL. AND NAT. HIST. SURVEY. [Bull. 



Family COCCIDAE. 



Scale Insects. 



By Wilton Everett Britton, Ph.D. 



The insects of this family differ from all other forms in the 

 females, for the most part, being non-motile and attached to the 

 host plants. On hatching both sexes crawl about for a few hours, 

 then become located on the host plant and feed by sucking its sap. 

 The mealy bugs (genus Pseudococcus) are an exception, and are 

 motile during the period of their existence after hatching from the 

 eg^s. The males pass through a true pupa stage and emerge with 

 a pair of wings, but the females have no pupa stages and pass 

 through several molts, gradually increasing in size and losing all 

 organs not necessary for their existence. 



Not only are scale insects of interest on account of their abnor- 

 mal morphology and peculiar life histories, but the family is of 

 great economic importance. Some of the worst insect enemies 

 of cultivated plants belong to the Coccidae. A large proportion 

 of our species are not indigenous but have come to us on plants 

 from other countries. Many tropical species have likewise been 

 introduced into greenhouses and some of them require periodic 

 treatment in order to keep them in subjection. On the other hand, 

 lac, which is used extensively in commerce, and forms the body 

 of spirit varnishes and certain printers' inks, is a product of 

 Asiatic scale insects ; likewise the dye-stuff, cochineal, is obtained 

 from the dried bodies of a Mexican species, though in recent years 

 this has largely been superseded by aniline dyes. 



Literature. 



Britton, W. E. The San Jose Scale Insect: Its Appearance and Spread in 

 Connecticut. Bulletin No. 135; reprinted in Report for 1901, p. 240; 

 revised and issued as Bulletin No. 165, Connecticut Agricultural Experi- 

 ment Station, New Haven, Conn. 



— The Chief Injurious Scale Insects of Connecticut, Bulletin No. 



151 ; revised and reprinted in Report for 1905, p. 234, Conn. Agr. Expt. 

 Sta., New Haven, Conn. 



Cockerell, T. D. A. The Food Plants of Scale Insects (Coccidae). Proc. 

 U. S. National Museum, Vol. xix, p. 725, 1897. 



Tables for the Identification of Rocky Mountain Coccidae (Scale 



Insects and Mealy Bugs), Univ. of Colorado Studies, Vol. ii, p. 190, 

 1905. 



Comstock, J. H. Reports on Scale Insects, from Report of U. S. Commis- 

 sioner of Agriculture, 1880; reprinted as Bulletin 2>7 2 , Cornell Univer- 

 sity Agricultural Experiment Station, Ithaca, N. Y., 1916. 



Cooley, R. A. The Coccid Genera Chionaspis and Hemichionaspis. 

 Special Bulletin Mass. Agr. Expt. Sta., Amherst, Mass., 1899. 



Dietz, Harry F., and Morrison, Harold. The Coccidae or Scale Insects of 

 Indiana, office of the Entomologist, Indianapolis, Ind., 1916. 



Fernald, Maria E. A Catalogue of the Coccidae of the World. Bulletin 

 No. 88, Mass. Agr. Expt. Sta., Amherst, Mass., 1903. 



