10 COXXECTICUT GEOL. AND NAT. HIST. SURVEY. [Bull. 



Most of the species of Hemiptera probably have only one gen- 

 eration each year. Some of the leaf-hoppers have two or more, 

 the San Jose Scale (Coccidae) has two broods in Connecticut, 

 and tropical or semitropical species of Coccidae occurring on plants 

 in greenhouses probably breed continuously without regard to 

 season. The life histories of many species are not well-known 

 and some are entirely unknown. 



Undoubtedly the aphids exceed all other species of insects in 

 the number of annual generations. Though the winter is usually 

 passed in the tgg stage, some species winter as adults. Of other 

 species as many as thirteen generations are known to occur in a 

 single season, most of these being born alive (viviparous) without 

 the intervention of males. This habit enables them to multiply 

 very rapidly and consequently they are among the most important 

 pests of cultivated plants. 



Several writers have pointed out that no order of insects has 

 been more neglected by entomologists or is more directly con- 

 nected with the welfare of the human race than the Hemiptera. 

 The Parasitica all live upon mammals, sucking their blood, and 

 include some of the most important pests of man and the domestic 

 animals. The Homoptera all suck the juices from the leaves or 

 twigs of plants, many species being markedly injurious. Thus 

 the members of the family Cicadellidae feed upon the leaves and 

 are known as "leaf-hoppers," those of the Membracidae feed upon 

 the stems and twigs and are called "tree-hoppers," the Fulgondae 

 or "lantern flies" are usually on the stems or leaves of herbaceous 

 plants or shrubs. The Cercopidae, known as "frog-hoppers" or 

 "spittle insects," make frothy masses on the stems of grasses or 

 the twigs of trees and shrubs. The members of the Cicadidae, 

 or "harvest flies," are larger than those of the families just men- 

 tioned and apparently with all the species the immature forms are 

 subterranean and feed upon the roots of trees : the adults suck 

 sap from twigs and branches, and lay their eggs in them. The 

 best-known and most destructive species in this family is the 

 "periodical cicada" or "seventeen-year locust." The Psyllids, or 

 "jumping plant lice," occur on the stems and leaves of woody 

 plants, and only a few species are considered as pests. The 

 Aphids, or "plant lice," are very abundant as regards species and 

 individuals and are common to nearly every plant species. They 

 are usually found on the under surface of the leaves or on the 

 tender shoots, often doing great damage. The Aleyrodids, or 

 "white flies," are few in number of species, and occur on the under 

 side of leaves. Only two or three species in our range are con- 

 sidered of economic importance. The Coccidae, or "scale insects," 

 occur on the bark and leaves of trees, the stems and leaves of 

 herbaceous plants and shrubs, and certain species are found in the 

 nests of ants : they are fairly abundant and include a number of 

 important pests. 



