328 MAUD D. IIAVILAND 



Aphides, with their parasites and hyperparasites, form 

 a bionoinical complex of considerable intricacy ; hut its limits 

 are well defined, and it is thus convenient for the study of the 

 bionomics of parasitism. The Ajjhidiidae, which are a lar»e 

 and distinct sub-family of Braconidae, are all obligative 

 parasites of Aphides, and have no alternative hosts ; and the 

 hyperparasites, which belong to the three super-families of 

 Cynipoidea, Chalcidoidea, and Proctotrypoidea, are exclusively 

 confined to the Apliidiidae, with the exception of certain 

 Cynipids (Charipinae) and C'halcids, which possess allied forms 

 parasitic upon Coccidae. 



The l)ionomics of some members of this complex are com- 

 paratively simple. Thus, the species of Charips (Cynipidae) 

 described elsewhere (6) are invariably parasites of Aphidius, 

 and thus hyperparasites of the aphid, and, so far as is known, 

 never prey upon another hymenopteron. The status of such Proc- 

 totrypids as L y g o c e r u s (5). and Chalcids such as A s a p h e s 

 and Pachycrepis, is more difticult to determine, because 

 although usually parasites of A p h i d i u s , and therefore 

 standing in the same relation to the aphid as Charips , they 

 may on occasion be parasitic on each other. The interrelations 

 of these forms are shown in the accompanying diagram (Text- 

 fig. 7). An Aphidius cocoon is sometimes found to contain 

 two hyperparasites of either, or both these species, the result 

 of two successive ovipositions. Fiske (3) has called this phase 

 of parasitism ' superparasitism ' ; but as the word means 

 neither more nor less than hyperparasitism, a term already 

 employed in cases where the parasite is itself attacked by 

 a parasite, I would suggest replacing this etymological hybrid 

 by ' epiparasitism '. In such a case, in the aphid complex, 

 only one imago emerges from the cocoon. Either one parasite 

 is sufficiently advanced to devour the host before its rival 

 can compete with it : or else, if both parasites are of the same 

 age, there is insufficient food to nourish both up to meta- 

 morphosis, and they starve to death. One seems never to make 

 a direct attack on the other. 



But in certain instances a Chalcid hyperparasite larva. 



