BIOLOGY OF SOME COMMON LAMPYRID.E. 



59 



AO 



chewed, like vegetable food or decayed animal tissues, and hence 

 it seems that some such method of feeding became necessary. 

 Some have the mandibles grooved, as the larvae of the Chry- 

 sopidse and Myrmeleonidae, while others have them pierced by a 

 small canal, such as certain of the larvae of the Dytiscidse and 

 Lampyridae. 



The most extensive work on this subject was done by two Euro- 

 pean workers, Vogel (1912, 1915) and 

 Haddon (1915), although earlier work- 

 ers made a less detailed study of the 

 problem. 



When the head of this insect is 

 withdrawn into the thorax, only the 

 tips of the mandibles and other mouth- 

 parts are visible, but when it is ex- 

 tended the large mandibles surrounded 

 by the other mouth-parts can be dis- 

 tinctly seen. 



As the anterior half of the mandib- 

 les are exposed on the dorsal side, the 

 labrum lies considerably caudad on 

 the head, extending across the basal 



FIG. 10. Plioturus pennsyl- 



portions of these large jaws. It is mw/ca larva, left mandible, dor- 

 rounded On the lateral margins, while sal view. AO, anterior opening 

 on its cephalic border are three prom- of mandibuiar canal; c, con- 



r . . ... dyle; PO, posterior opening of 



inent forward projecting portions with .... . ~ . ,, 



mandibuiar canal; T, tooth on 



rather acute terminations. Its dorsal inner edge of mandible. 

 side (Fig. 9), shows numerous long 



projecting bristles while the ventral side is covered with a rather 

 dense mass of small setae which project forward. 



The mandibles (Fig. 10) are very strong. Each has a large 

 curved, anterior tapering tooth and they meet in a median line 

 slightly anterior of the head. On the inner median margin of 

 each mandible is a secondary tooth (7"). At the base is a knob- 

 like condyle (C) by which the mandible articulates with the head. 

 Both mandibles are covered for their entire extent with setae of 

 varying length, except at the distal end, and around the condyle. 

 About the base is a dense brush of short setae which project for- 



po 



