PEELIMIlSrAEY CLASSIFICATIOlSr OF SCOLYTOIDEA, 207 



Table VII. — Relation of groups of galleries to the families of Scolytoidea. 



Groups. 



Ipidse. 



Scoly- 

 tidse. 



Scolyto- 



platy- 



podidse. 



Platy- 

 podidse. 



Division 

 I. 



Division 

 II. 



1 



2 



3 



4 



5 



6 



7 



8 



Genera. 

 5 

 4 

 9 

 3 

 4 

 2 

 3 

 



Genera. 

 5 

 3 

 

 2 

 1 

 S 

 2 

 9 



Genera. 

 

 

 

 

 1 

 1 

 2 

 1 



Genera. 



'o 





 1 

 

 

 

 

 



Genera. 

 

 

 2 

 

 

 

 

 



In Hypothenemus the types of galleries do not extend beyond 

 group 1 and represent specific types a, h, c, and d; CrypJialus is also 

 confined to the same group and types, while Pityophthorus repre- 

 sents group 1, a and d; group 4, a, h, c, and d; and group 5, a and d. 

 Ips represents group 2, a, h, c, and d, and group 5, a, h, c, and d. 



The relation of types of galleries to species shows some striking 

 examples of progressive modification within a genus and of parallel 

 characters in different genera. It is not desirable to present a table 

 to illustrate these relations in this connection, but it is intended to 

 do so in subsequent parts dealing with the subfamilies. 



While considerable attention has been given to the subject, a far 

 more comprehensive study of the egg and brood galleries than has 

 yet been made is required as a basis for correlating their taxonomic 

 characters with the morphological characters of the species. 



TAXONOMIC RELATION BETWEEN THE BEETLES AND THEIR HOST 



PLANTS. 



Among the scolytoid beetles there is often a close taxonomic 

 relation between the species, genera, and groups of the beetles and 

 the species, genera, or groups of plants they infest, so that we may 

 often know the insect by the host, or the host by the insect. 



In other words, the host, together with the character of the gallery 

 of a beetle, will often not only serve to identify the species to which 

 it belongs but will indicate its systematic position. In a like manner 

 the presence of certain species of beetles will serve to identify the 

 species of plant and indicate its systematic position. 



Part of Plant Selected by the Beetles. 



The part of the plant in which the egg galleries are excavated is 

 also of interest. In some species it is limited to the root or stem of 

 an herbaceous plant; in others to the bark on the roots, main trunk, 

 larger branches, and smaller branches, or to the twigs or fruit of a 



