FIELD BOOK OF INSECTS. 



COLEOPTERA 



Beetles may usually be recognized, when adult, by the 

 fact that their front wings ("elytra") are hardened. The 

 elytra usually do not overlap but meet in a line (the "su- 

 ture") along the middle of the back; in all Staphylinidse, 

 and in some other groups, they do not, however, com- 

 pletely cover the abdomen. They have chewing mouth- 

 parts. Metamorphosis is complete. The larvse have no 

 abdominal legs except (often) on. the last joint. Twelve or 

 fifteen thousand species are known from North America. 

 The student who desires to specialize is referred to the 

 following two books, from which many of the concise 

 descriptions given here have been copied: 



Blatchley, W. S. An illustrated descriptive catalogue of the 

 Colsoptera or Beetles (exclusive of the Rhynchophora} 

 known to occur in Indiana. 



Blatchley, W. S. and Leng, C. W. Rhynchophora or 

 Weevils of North-Eastern A merica. 



Coleoptera are divided by Sharp into the following six 

 series, not counting Strepsiptera (p. 405). For the con- 

 venience of American students, I have followed the order 

 of arrangement which is in general use in America. After 

 some familiarity with the various groups has been gained 

 by matching specimens with the pictures, the student will 

 be able to assign most beetles to their proper family on 

 "general appearance." 



ADEPHAGA. Tarsi 5-jointed, the fourth quite dis- 

 tinct; antennas thread-like or nearly so, never lamelli- 

 form; abdomen with one more exposed segment at the 

 sides than along the middle, the numbers usually being five 

 and six. See p. 281. 



POLYMORPHA. Antennas frequently with either a 

 club, i. e., the terminal joints broader than the others (the 

 Clavicorns), or the joints from the third onwards more or 

 less saw-like, the serrations being on the inner face (the 

 Serricorns) ; but these and all other characters, including 

 the number of joints in the feet, very variable. See 

 p. 292. 



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