248 



AN INTRODUCTION TO ENTOMOLOGY 



Fig. 266 

 sus. 



-Gryllus assimilis luctuo- 



The larger field-crickets, Gryllus. — The members of this genus are 

 dark-colored, thick-bodied insects of medium or large size. In these 



the hind tibiae are armed with strong 

 fixed spines and the first segment of 

 the hind tarsi is armed with two 

 rows of teeth above. There are 

 two auditory tympana in each fore 

 tibia. The length of the body is 

 rarely less than 14 mm. 



Many supposedly distinct 

 species of Gryllus have been de- 

 scribed as occurring in our faima; 

 but now all of our native forms are believed to be merely varieties of 

 one species, Gryllus assimilis, and the different varieties are distin- 

 guished by subspecific names. Six of these varieties that occur in 

 the East are described by Blatchley ('20). Two of these will serve 

 to illustrate our native forms. 



Gryllus assimilis luciudsus. — This is one of our more common 

 forms of the genus. It is distinguished by the great length of the 

 ovipositor of the female, which is nearly or 

 fully half as long again as the hind femora 

 (Fig. 266) ; and by the fact that the head of 

 the male is distinctly wider than the front 

 of the pronotum. 



Gryllus assimilis pennsylvanicus. — In 

 this variety the ovipositor is less than half 

 as long again as the hind femora, and the 

 head of the male is but little if any wider 

 than the front of the pronotum (Fig. 267). 

 In fresh specimens the color is not shining 

 black, but with a very fine grayish pubes- 

 cence. 



In addition to our native forms of Gryllus, 

 there is an Old World species that has been 

 introduced into this country; this is the 

 house-cricket, Gryllus domesticus. Refer- 

 ences to the "cricket of the hearth" are 

 common in English literature and refer to 

 this species, which is now widely distributed 

 in this country, though it is rarely abundant. 

 It is pale yellowish browTi or straw-colored, 

 and slender in form (Fig. 268). The length 

 of the body is 15-17 mm. 



Our native field-crickets sometimes enter 

 our dwellings in the autumn; but the house-cricket can be easily 

 distinguished from these. 



The smaller field-crickets, Nemobius. — To this genus belong the 

 little field-crickets, which are the most abundant of all of our crickets. 

 In these the hind tibiae are furnished with long, mobile, hairy spines. 



Fig. 267. — Gryllus assim- 

 ilis pennsylvani- 

 cus. (From Lugger.) 



