384 AN INTRODUCTION TO ENTOMOLOGY 



But little has been published regarding the habits of these insects. 

 It is evident, from the structure of their fore legs, that they are 

 predacious. Professor Johannsen ('09 b) found Systelloderus biceps 

 (Henicocephalus culicis) flying in small swarms near Ithaca, N. Y. 

 Their manner of flight resembled that of chironomids. They were 

 observed repeatedly from July 5 to the last week in August, always in 

 the latter part of the afternoon. This species measures 4 mm. in 

 length. 



The type genus of this family was first named Enicocephalus ; this 

 name was later emended to Henicocephalus; but the older form of the 

 name, though incorrectly formed, is now used. 



Family TINGID^ 



The Lace-Bugs 



The Tingidag are doubtless the most easily recognized of ail Hemip- 

 tera. The reticulated and gauze-like structure of the hemelytra, 

 usually accompanied by expansions of the pro- 

 thorax of a similar form, gives these insects a 

 characteristic appearance which needs only to 

 be once seen to be recognized in the future. 

 Figure 443 represents one of these insects 

 greatly enlarged, the hair-line at the side 

 indicating the natural size of the insect. They 

 are generally very small insects. But they 

 occur in great ntunbers on the leaves of trees 

 and shrubs, which they puncture in order to 

 suck their nourishment from them. 



In this family the ocelli are wanting; the 



beak and antennas are four-jointed; the scu- 



Fig- 443- — Corythucha tcUimi is usually wanting or vestigial, replaced 



arcuata. }^y. ^j^g angular hind portions of the pronotum; 



and the tarsi are two-jointed. 

 About seventy-five species of lace-bugs, representing twenty-three 

 genera, are now listed from this country. There are two well-marked 

 subfamilies. 



Subfamily TINGING 



This division includes nearly all of the known species. Here 

 the scutellum is usually covered by an angular projection of the 

 pronotimi ; and the hemelytra have no distinction between the clavus, 

 corium, and membrane. The following species will serve as an il- 

 lustration of this subfamily. 



The hawthorn lace-bug, Corythucha arcuata. — This is a widely 

 distributed species, which punctures the under surface of the leaves 

 of different species of Crataegus. The infested leaves have a brown 

 and sunburnt appearance. Eggs, n^-mphs, and adults are found 

 together. The adult is represented, much enlarged, in Figure 443. 



