HYPERPARA8ITISM 327 



sites, of a given insect, are immune from attacks by their own 

 specific parasites, which are termed hyperparasites or secondary 

 parasites. Hyperparasitism, consequently, is a significant factor 

 in the maintenance of the balance between insect species in Nature, 

 and the biological association of hosts, primary parasites and 

 secondary parasites is a highlj^ adjusted complex. It is probable 

 that hyperparasitism is a development of multiparasitism and, 

 in some cases, it is difficult to distinguish between the two 

 phenomena, since one may intergrade into the other. 



By far the largest number of hyperparasites are members of 

 the Ichneumon sub-families Cryptinse and Ophioninae, and of 

 various families of Chalcids, but it is among the latter group 

 that they are the most numerous. The Proctotrypoidea and 

 Cynipoidea also comprise a considerable number of hyperparasites. 

 Outside Hymenoptera secondary parasitism is very rare, and the 

 few known examples include certain Bombyliidse among Diptera 

 and two records among Coleoptera [vide Muesebeck and Dohanian, 

 1927). 



In frequent cases it is not possible to distinguish, absolutely, 

 certain species as primary parasites or as hyperparasites, since 

 their behaviour is plastic and largely determined by the types of 

 hosts adopted. Timberlake (1913), for example, found that the 

 Chalcid Coccophagus lecanii Fitch is a common primary parasite 

 of the soft scale (Coccus hesperidum), but, when associated with 

 other Chalcid primary parasites (Microterys or Aphycus), may 

 becomes hyperparasitic.^ The Chalcids Monodontomerus cereus 

 Walk, and Eupteromalus nidulans (Foerst.) occur as primary 

 parasites of the gipsy moth and brown-tail moth respectively, but 

 both species also frequently become hyperparasitic through 

 Braconid or Tachinid parasites of those hosts. Many examples of 

 this character are known, and further references will be found in 

 the excellent bulletin by Muesebeck and Dohanian. 



When two or more secondary parasites occur in the same 



^ It may be mentioned that Coccophagus is normally parthenogenetic and 

 thelyotokous, producing females generation after generation, but when it is 

 hyperparasitic, Timberlake states that the resulting progeny are all males. 

 This unique phase has been ascertained to be prevalent both in the field and 

 under laboratory conditions. 



