FIELD BOOK OF INSECTS. 



across each elytron, back of the middle, a yellow spot 

 back of this and sometimes one in front. On maple and 

 poplar. 



Clirysobothris azurea is usually a little more than .25 in. 

 long. Its color varies from blue to greenish, coppery, and 

 violet. Each elytron has the following brilliant blue or 

 green markings, which appear to be depressed : a somewhat 

 variable streak or combination of spots at the base, one 

 circular spot near the middle, and one two-thirds of the 

 way to the apex. On birch, sumac, and dogwood. 



Bracliys The several species of this genus are leaf- 

 miners and abundant. The adult larva makes a curious 

 noise, within the mined leaf, by switching his body rapidly. 



Herbaceous Plants 



Pacliyscelus purpureus mines in the leaves of the bush- 

 clover (Lespedeza). The adult is usually less than .2 in. 

 long and the shoulders are so broad that, from above, it 

 looks hunched up. The head and pronotum are black; 

 elytra, purple. 



LAMPYRID^: 



Nearly all Americans who are blessed with eyes have 

 seen Fireflies and many have seen Glowworms. These 

 insects belong to this family but most of the species of 

 Lampyridas are not luminous. A family characteristic 

 is that the elytra, when present, are thin and flexible; 

 there are seven or eight visible, ventral, abdominal seg- 

 ments. For the most part, the species are predaceous, 

 especially as larvae. The larvae usually live under rubbish 

 or the bark of logs and dead trees. 



Folsom says: "In Lampyridae, the light is emitted from 

 the ventral side of the posterior abdominal segments. In 

 our common Photinus, the seat of the light is a modified por- 

 tion of the fat-body a, photogenic plate, situated immedi- 

 ately under the integument and supplied with a profusion 

 of fine tracheal branches. The cells of the photogenic 

 plate, it is said, secrete a substance which undergoes rapid 

 combustion in the rich supply of oxygen furnished by the 

 tracheae. 



