174 BULLETIN 66, UNITED STATES NATIONAL MUSEUM. 



APPENDICES. 

 PARASITISM. 



Certain characteristics or laws of parasitism may be framed as a 

 general summary of the results found in the article. 



I. The fact that a certain peculiarity is possessed by two insects 

 in varying degrees does not indicate close relationship. 



(1) The abortion, or loss of wings, occurs in Coleoptera, Diptera, 

 Strepsiptera, Dermaptera, Homoptera, Orthoptera, and Hymenop- 

 tera. 



(2) The wingless female occurs in Coleoptera, Lepidoptera, Strep- 

 siptera, Hymenoptera, and Homoptera. 



(3) The "raspberry" eye occurs in Diptera (Pupipara), Strepsip- 

 tera, and Thysanoptera. 



(4) Hypermetamorphosis occurs in Coleoptera, Neuroptera, Hy- 

 menoptera, and Strepsiptera. 



(5) Larviparous reproduction occurs in Homoptera, Strepsiptera, 

 and Diptera. 



(6) Flabellate antennae occur in Coleoptera, Strepsiptera, and 

 Hymenoptera. 



II. Two lines of descent may arise from greatly variant sources 

 and through the assumption of similar habits of life develop organs 

 closely approximating each other. Or two different combinations of 

 causes may exert influences inducing an approximation of resultant 

 organs. 



(1) The Meloidse, Rhipiphoridae, and Strepsiptera have the first 

 larval stages similar. 



(2) The antennas of the Rhipiphoridae are flabellate, as they are 

 also in male Strepsiptera. 



(3) The mouth parts of the Rhipiphoridae and Strepsiptera are 

 atrophied. The peculiar rhipiphorid Rliyzostyloys inquirendus Sil- 

 vestri may be referred to in this connection. 



III. Parasitism is an acquired habit; an adaptation— hence a 

 specialization. In the specialized adaptation to a parasitic life cer- 

 tain organs become unnecessary and are changed to accomplish new 

 functions or become aborted or lost. Certain other organs at the 

 same time have an increase of function or assume duties entirely new, 

 and consequently through selection and modification induced by 

 changed functions become very different from the type organs. 



(1) In the Strepsiptera the first change noted is the loss of legs and 

 eyes by the larva, and the ultimate recovery of these organs by the 

 male, but the final loss of them by the female. 



(2) The reduction of the male front wings to clubs is accompanied 

 by the assumption of the function of sound making. 



(3) The female's permanence in one position has brought about 

 the complete reduction of all appendages except the mandibles 



