178 Hosts of Insect Eggparasites in Europe, Asia, Africa and Austraiasia. 



Eacyrtidae Tyndarichus Howard 



Fulgoridicida Perkins 

 Ectopiognatha Perkins 

 Leurocerus Crawford 

 Eurytomidae Rüeyini (mostly) 



Callimomidae Podagrion Spiuola 



Pachytomuides Girault Ü 



Scelionidae All. 5} 



Evaniidae Evania 



Parasites of insect eggs over the entire earth seem to be over 

 whelmingl}^ hymenopterous. For an exception, see the second part 

 my American list (Girault, 1911a) where an imknown Dipterous egg 

 parasite is recorded. All (with the one exception) of the parasites 

 embryonic insects are included within the great group of the Hyineno 

 ptera Parasitica where all the species are parasitic lipon insects or thei: 

 allies, with the exception of some small tribes which are ph^^tophagous 

 Of these great complexes of the Hymenoptera Parasitica, however, th« 

 parasitism of embryos is present usually only in those groups wliicl 

 comprise species of small stature. These are, of course the Chalcidoidec 

 and the Proctotrypoidea', of the Ichneumonoidea only the anomalvuf 

 Evaniidae parasitize eggs. In the first two great groups, size agaii 

 seems to be related to the habit of parasitizing embryos, for the smalles' 

 of them, namely the Mymaridae and the TrichogrammaUdae arf 

 exclusively of this habit. The relation, in a word, is so striking tlia 

 this habit appears to be a secondary adaptation of the parasites to theii 

 hosts. One could conclude from this that the parasites of small size 

 Unding the eggs of insects suitable and sufficient as food for theii 

 progeny, gradually adopted them as their food and hosts, abandoniü^ 

 their former larval hosts.*) Parasitism, from its very nature, must b( 

 of secondary origin. The first animals could not have been parasites 

 the first insects could not have been insect parasites. Parasitism 

 insects upon insects is of secondary origin, an adaptive habit. Wi 

 know this from the phylogen^^ of insects and from the present survivin^ 

 habits of the great majority of them. The tendency to simplificatior 

 or to specialization present in all parasites is another evidence in favom 

 of this fact. Parasitism of the eggs of insects does not diflfer fron 

 parasitism of the larva and there is no especial reason why insect egg 

 parasites should alwaj^s be Hymenopterous. We have some reason foi 

 believing, however, that the parasitism of insect embryos is a latei 

 adaptation, since for one thing insect egg-parasites themselves ar( 

 probably later phylogenetic developments. More than this, they are 

 small size while their ancestors were of large stature; also they ar( 

 exceptions in the groups to which thej" belong and appear to b( 

 descendents, rather than precursors or cotemporaries, of their allies 

 Taken as a whole, they also seem highlj^ adaptive and variable; ii 

 some of them, the capacity for rapid reproduction and successiou 

 developmental cycles is enormous (e. g. Trichogramma minutuni)^ sur 

 passing, no doubt that of auy other insects. (Schluss folgt.) 



*) On tlie other band, it is posslble that the small size of eggparasites is 

 due to the effect of their hosts, the amount of food not being sufficient tc 

 produce largeness. But 1 do net believe this is probable from the nature 

 the case. 



