HOW TO KNOW THE INSECS 



12b Abdomen with five visible ventral segments; epimera of the 

 mesathorax not reaching the coxae, (a) (The Skin Beetles) Fig. 97. 



Fami ly 98, TROGIDAE 



Fl^. 97. Trox fflonachus Hbst. 



Dull grayish black, roughened with warty 

 tubercles. One of a small family of heavy 

 set thick bodied beetles found on skins and 

 bones of carrion. Length 13-16 mm. 



One may often find several species of this 

 little fajnily flying to the lights at night. 

 An old slaughter house is a good place to look 

 for them. They are frequently so encrusted 

 with dirt that they must be cleaned before 

 accurate identification is possible. 



Figure 97. 



13a Antennae not elbowed. Mentum deeply eraarginate, the ligula 

 filling the notch. Fig. 98. Family 100, PASSALIDAE 



Fig. 98. Passalus cornutus Fab. The Horned 

 Passalus. 



Length 32-37 mm. Shiny black v/ith a short 

 horn bent forward on the top of the head. Both 

 adults and larvae found in decaying wood. Our 

 only Iowa species of the family. 



I'^igure 98. 



13b Antennae nearly always geniculate (elbowed); mentum entire. 

 (The Stag Beetles). Fig. 99. Family 99, LUCANIDAE 



Fig. 99. Pseudolucanus capreolus (L.) "The 

 Pinching Bug. " 



Dark reddish brovm, femora light brown. Man- 

 dibles of female only half as long as those of 

 male, here shov/n. Frequently fly to lights. 

 Length 22-35 mm. 



We have only a few species of stag beetles 

 but because of their threatening ways they are 

 well known. The adults are said to live on 

 plant secretions and honey dew. The larvae are 

 found in decaying wood. 

 14a Hind legs modified for swimming; Antenna clavate or 

 capitate. (The genus Sphaeridi urn belonging here, does not 

 have swimming legs.) (The Water Scavenger Beetles) 



Figure 99. 



Fig. 100. 



60 



Family 8, HYDROPHILIDAE 



