No. 1 6.] ORTHOPTERA OF CONNECTICUT. 57 



remedy against this insect is to fumigate the infested rooms with 

 hydrocyanic acid gas. This gas is fatal to all animal life, so 

 that its use is only practicable where the kitchen is isolated from 

 the other part of the house, or where it can be shut up tightly. 

 Carbon disulphide has been recommended, but this is quite in- 

 flammable and has a disagreeable odor. Borax and pyrethrum 

 (insect powder) are often used as repellents. Burning the 

 pyrethrum powder wdll kill and stupefy many of the insects. 



PERI PLAN ETIN,^. 



This sub-family contains our largest cockroaches. These are 

 introduced species ; and one of them, the most disgusting of all 

 our roaches, is well known. The chief distinguishing characters 

 are given in the key. The head is large, flattened, and not en- 

 tirely covered by the pronotum. The antennae are more or less 

 pubescent, the joints obconic and very short. The tegmina and 

 wings are variable in the different species. In our species the 

 hind tarsi have the first joint as long as, or longer than, the 

 other two joints together. 



Key to Genera. 



Tegmina of the male covering about three-fourths of the 

 abdomen, those of the female much shorter. Distance 

 between the eyes greater than length of last joint of 

 maxillary palpus Blatta p. 57 



Tegmina of both sexes extending beyond tip of abdomen. 

 Distance between the eyes less than length of last joint 

 of maxillary palpus Periplaneta p. 58 



Blatta Linnaeus. 

 This genus is recognized by the more widely separated eyes 

 which are farther apart than the distance between the antennal 

 pits or scrobes. The tegmina are short in both sexes, especially 

 so in the female, and their outer edges less rounded than in 

 Periplaneta. 



B. orientalis Linnaeus. Oriental Cockroach. Black Beetle. 

 Plate VII, 4. 



Dark mahogany brown, legs lighter. Pronotum without light 

 margins or markings. The wing covers of female not over 



