MALLOPHAGA. 233 



MALLOPHAGA. 

 By 



CHARLES ALBP^RT SHULL AND M. A. CARRIKER, JR. 

 INTRODUCTION. 



Among the smaller orders of insects, none offers more interesting 

 problems to the biologist than the Mallophaga. Until recent years 

 little attention had been given to these obscm-e parasitic forms ; but the 

 splendid work of Kellogg and others in the closing years of the last 

 centmy aroused much interest in them, and has led to a constantly and 

 rapidly increasing knowledge of the order. 



One of the problems which must be more fully investigated is that of 

 the distribution of the various species, not from the geographical stand- 

 point, for this depe^nds upon the distribution and migration habits of 

 the hosts, but from the standpoint of host distribution of the insects. 

 More information is imperative before any general conclusions con- 

 cerning the order can be drawn. 



Many of the species are as yet reported from but a single host, and, 

 indeed, the presence of certain species of Mallophaga on certain hosts 

 is in many instances so characteristic that the relation has proven one 

 of the surest means of identification to the amateur. It is usual to 

 find that any particular species is confined to a small group of closely 

 related hosts, and that within a group of hosts some of the parasites 

 may be of close relationship. The possible significance of these facts 

 in tracing the lines of evolution among the birds and Mallophaga must 

 not be overlooked, but no sure conclusions can be drawn until a far 

 greater mass of data on the distribution has been accumulated. Gen- 

 eral distribution on varied hosts ma,v indicate antiquity, and restric- 

 tion a more recent origin. The presence of a single species on a 

 few closely related birds may be accounted for by supposing that 

 the parasite inhabited the ancestral birds, and has been transmitted 

 unchanged to all the branches of the family. The importance of a 

 fuller study is seen at once, and any contribution to the knowledge of 

 these insects is of great biological interest. 



HINTS ON COLLECTING. 



In order that records may be accurate, the collector of Mallophaga 

 should remember that when a bird has been killed and the bodv be- 



