178 Hosts of Insect Eggparasites in Europe, Asia, Africa and Australasia. 
Encyrtidae Tyndarichus Howard 
Fulgoridieida Perkins 
Eetopiognatha Perkins 
Leurocerus Crawford 
Eurytomidae Rileyini (mostly) 
Callimomidae Podagrion Spinola 
Pachytomoides Girault 
Scelionidae | All. 
Evaniidae Evania 
Parasites of insect eggs over the entire earth seem to be over- 
whelmingly hymenopterous. For an exception, see the second part of 
my American list (Girault, 1911a) where an unknown Dipterous egg- 
parasite is recorded. All (with the one exception) of the parasites of 
embryonic insects are included within the great group of the Hymeno- 
‘ptera Parasitica where all the species are parasitic upon insects or their 
allies, with the exception of some small tribes which are phytophagous. 
Of these great complexes of the Hymenoptera Parasitica, however, the 
parasitism of embryos is present usually only in those groups which 
comprise species of small stature. These are, of course the Chalcidoidea 
and the Proctotrypoidea; of the Ichneumonoidea only the anomalvus 
Evaniidae parasitize eggs. In the first two great groups, size again 
seems to be related to the habit of parasitizing embryos, for the smallest 
of them, namely the Mymaridae and the Trichogrammatidae are 
exclusively of this habit. The relation, in a word, is so striking that 
this habit appears to be a secondary adaptation of the parasites to their 
hosts. One could conclude from this that the parasites of small size, 
finding the eggs of insects suitable and sufficient as food for their 
progeny, gradually adopted them as their food and hosts, abandoning 
their former larval hosts.*) Parasitism, from its very nature, must be 
of secondary origin. The first animals could not have been parasites; 
the first insects could not have been insect parasites. Parasitism of 
insects upon insects is Of secondary origin, an adaptive habit. We 
know this from the phylogeny of insects and from the present surviving 
habits of the great majority of them. The tendency to simplification 
or to specialization present in all parasites is another evidence in favour 
of this fact. Parasitism of the eggs of insects does not difier from 
parasitism of the larva and there is no especial reason why insect egg- 
parasites should always be Hymenopterous. We have some reason for 
believing, however, that the parasitism of insect embryos is a later 
adaptation, since for one thing insect egg-parasites themselves are 
probably later phylogenetic developments. More than this, they are of 
small size while their ancestors were of large stature; also they are 
exceptions in the groups to which they belong and appear to be 
descendents, rather than precursors or cotemporaries, of their allies. 
Taken as a whole, they also seem highly adaptive and variable; in 
some of them, the capacity for rapid reproduction and succession of 
developmental cycles is enormous (e. g. Trichogramma minutum), sur- 
passing, no doubt that of any other insects. (Schluss folgt.) 
ei On the other hand, it is possible that the small size of eggparasites is 
due to the effect of their hosts, the amount of food not being sufficient to 
produce largeness. But I do net believe this is probable from the nature of 
the case. 



