THE ALYDINiE OF THE UNITED STATES. 



By vS. B. Frackkk, Madison, Wisconsin. 



The family Coreidae consists of five subfamilies, two of 

 which, the Merocorinae and Pseudophloeina?, are very small. 

 The larger divisions, often ranked as families themselves, are: 

 Corizinae, characterized by a mesal constriction of the fourth 

 dorsal abdominal segment and the obsolescence of the scent- 

 gland orifices; Alydins, distinguished by the wide head and 

 unusually small bucculse; and Coreinse, which, together with 

 the smaller groups named above, includes the rather diverse 

 remaining members of the family. 



The Alydinas form a compact and easily recognizable group 

 found in all parts of the world and include several cosmopolitan 

 genera. Those occurring in the United States all possess a 

 head at least three-fourths as wide as the pronotum and all 

 except the last two genera have well developed and conspicuous 

 scent gland orifices in front of the posterior coxee. The bucculas 

 are short, not surpassing the insertion of the antenna? and the 

 scutellum is narrower than the intraocular part of the head. 



In this paper eleven genera, nineteen species and seven 

 varieties are recognized, of which one species and three varieties 

 are new. Material was available in all except three subtropical 

 species (numbers 3, 4 and 8) each of which has been reported 

 from the United States only once. The discussions of these 

 three are based on the descriptions. 



Eight of the species found in the United States, and six of 

 the genera, are subtropical, and are confined to the southern 

 tier of States. Four are probably limited to the Rocky Moun- 

 tains and Pacific coast, and three almost entirely to the States 

 north of the Ohio River. The remaining four have been col- 

 lected in nearly every part of the United States. P rote nor 

 belfragei, Megalotomus 5-spinosus, Alydiis eurinus, and A. 

 conspersus are among the most common Heteroptera of the 

 temperate zone. 



No members of the subfamily are known to be of economic 

 importance. The common species are found in meadows or 



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