HOW TO KNOW THE IMMATURE INSECTS 



19a. Apex of mandible multiserrate; cerci short, 1-segmented. 



Fig. 187 Family PTILIIDAE 



Fig. 187. a, Nossidium omeri- 



conum Mots.; b, Mandible. 



The larvae and adults of these 'feath- 

 er-winged" beetles live in decaying 

 wood, fungi and in ant's nests. They 

 are very minute, some of the smallest 

 known beetles belong to this family. 



19b. Apex of mandible biiid or trifid; cerci 2-segmented, last segment 

 often multianniilated. (See Fig. 188) 20 



20a. Mandible with vestigial retinaculum. 



Fig. 188 Family LEPTINIDAE 



This is a very small family. Its hab- 

 its are practically unknown but they 

 have been found in rotten wood, in the 

 nests of birds and of field mice. 



Fig. 1 88. a, Leptinus testoceus 



Mull; b, Mandible. 



20b. Mandible with distinct retinaculum or prostheca, or both. 



Fig. 189 Subfamily Anistominae, SILPHIDAE 



They are found among damp herb- 

 age, in fungi, under bark, etc. They 

 are fairly abundant but their very 

 small size results in their being 

 rather poorly known. 



Fig. 189. a, Prionochaeto 



Soy; b, Mandible with retinaculum; 



c. Mandible with prostheca. 



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