4 2 2 CONNECTICUT GEOL. AND NAT. HIST. SURVEY. [Bull. 



Family MIRIDAE (CAPSIDAE).* 

 By Harry Hazelton Knight, Ph.D. 



The family Miridae, or Capsidae of older authors, is distin- 

 guished by having four-segmented antennae, four-segmented ros- 

 trum of which the first segment is as long or longer than the head, 

 by absence of ocelli, tarsi three-segmented, wing membrane with 

 only two cells or areoles, one longitudinal vein (anal vein), and 

 by having a well developed cuneus in the wing (Fig. 47). The 

 four-segmented antennae are usually slender, nearly linear or 

 segment ii only slightly thickened apically, but more rarely strongly 

 incrassated ; segments iii and iv usually slender but in some forms 

 distinctly thickened. The hemelytra are typically separated into 

 clavus, corium, cuneus, and membrane, the embolium usually not 

 clearly separated from corium ; veins of membrane forming two 

 cells, a smaller and a larger areole. The arolia, or pulvillae-like 

 structures between the tarsal claws, in their modifications furnish 

 the most reliable characters for separating the subfamilies. 



In general, the species of Miridae are small to medium in size, 

 usually rather fragile, broader than high and longer than broad; 

 as viewed from above ovate to oblong, but at times very slender. 

 Usually the male is more slender than the female. The body is 

 variously clothed with fine hairs or pubescence, sometimes modified 

 to form sericeous, or scale-like, deciduous pubescence; frequently 

 the dorsum practically glabrous and strongly shining. The 

 numerous species exhibit the greatest variety of color patterns, 

 ranging from the most obscure to forms which are vivid red. 

 Color varieties within the species are frequent, and the two sexes 

 are more often differently colored, the male usually darker than 

 the female. 



Brachypterous and apterous forms occur throughout the family, 

 and individuals of a single species may exhibit variation in this 

 respect. Usually the male is macropterous even when the female 

 is apterous, but the male may in rare cases also be apterous. 

 Mimetic forms are rather numerous among the Miridae, especially 

 those species described in genera closely related to Pilophorus. 



Perhaps a majority of the species of Miridae are plant feeders, 

 but a large number are now known to be chiefly predaceous. The 

 predaceous habit is only partially developed in certain species, and 

 thus animal blood serves merely to supplement the sap obtained 

 from particular food plants. Probably the greater number of 

 species are limited to a single host plant, or to a genus of plants, 

 while a very few, such as Lygus pratensis Linnaeus and Halticus 

 citri Ashmead, have a wide range of food plants. Forms which 

 are chiefly predaceous are more frequently found on miscellaneous 



* Contribution from the Department of Entomology, University of 

 Minnesota. 



