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 oirr faima; 



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



one species, Gryllus assvnilis, 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 luctuosus. — 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 pennsylvdnicus . — 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 coimtry; 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 brown 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 abtmdant of all of our crickets. 



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



Fig. 267. — Gryllus assim- 

 ilis pennsylv ani- 

 cus. (From Lugger.) 



