February, '10] FISKE : SUPERPARASITISM 



89 



for observation, and in every case but one there was no development to 

 maturity of either the dipterous or the hymenopterous parasite. In 

 one case, however, an adult of the Tachinid Euphorocera claripennis 

 issued from such a caterpillar. The probabilities are that its larva 

 was already well grown when its host was stung by the Pimpla and 

 that the larvge of the latter failed to find sufficient nourishment for 

 development. 



''Such instances would seem to show that the maternal instinct is 

 not so prescient as has been supposed, and that all the preliminary 

 ijivestigation of the host insect by the mother parasite and all the 

 apparently anxious soundings and tappings with her antenna, while 

 appearing to satisfy her that everything is all right, do not always 

 result in the depositing of the eggs under just the proper conditions. 

 It is altogether likely that other parasitic HjTuenoptera occasionally, 

 and perhaps frequentl}^, make similar mistakes, and that many para- 

 sites suffer from this rivalry based upon erroneous instinct, as well as 

 from the attacl^ of hyperparasites. Such mistakes are, of course, 

 much more likely to occur during such times of extraordinary multi- 

 plication than when the species are normally abundant." 



Upon other occasions, similar observations have been made and 

 conmiented upon both in Europe and in America, but in no case 

 which has come to the attention of the writer has their significance 

 been so clearly understood as is indicated by the above quotation. It 

 is his present opinion that such double parasitism is of much more 

 than incidental and academic interest. 



In the brief account of the parasites which had been reared from the 

 cocoons of Saniia cecropia and Callosamia promethea, which appeared 

 in No. 6 of the second volume of the Journal, something was said 

 of the various forms of double parasitism which were encountered. A 

 large number of other observations of a similar nature are recorded in 

 the note files at the Gypsy IMoth Parasite Laboratory, and from time 

 to time, as opportunity permits, it is hoped and intended to publish 

 certain among the more interesting and suggestive of these. For the 

 present it is merely intended to propose the term superparasitism to 

 designate these phenomena, to define this term, and to attempt to 

 demonstrate the importance of the principle involved in the natural 

 control of insects. 



Definition. Superparasitism results when any individual host is 

 attacked by two or more species of primary parasites, or by one species 

 more than once. It differs materially from secondary parasitism, or 

 hyperparasitism as it is variously called, although both are, strictly 

 speaking, double parasitism of an individual. In superparasitism the 



