682 BIOLOGY OF CHALCIDID.E HOWAHD, 



mils. The number developiDg' in a single host depends (a) upon the size 

 of the host and {b) upon the sizeof the parasite. Six or eight speciineus 

 of a little Gopidosoma will issue from the larva of a Lithocolletis, while, 

 as actual count has demonstrated, over 2,500 specimens of a congeneric 

 species of the same size will issue from the larva of a PJnsia. The num- 

 ber varies in this instance from some cause from this down to something 

 over a thousand. Between tlieextremes there is every gradation. Usually 

 a single Cocco})hagus inhabits a single 3Iytilas2)iSj but from two to six 

 specimens of Goccophagus lecanii issue from Lecanium hesjieridum, while 

 thirteen specimens of the same species have been reared from Lecanium 

 qiiercitronis. From two to four specimens of Triehogramma minuta will 

 issue from' a single egg of Basilarcliia archippus, from three to eight 

 specimens of HomalotyJ us ohsciirus from a single larva ofMegilla maeuJnta, 

 from ten to thirteen specimens of Bothriothorax peculiaris from a full- 

 grown larva of the syrphid genus Allograpta, from thirt^^ to forty speci- 

 mens of Cratotechufi hasalis from a larva of J)atana ministra, or from 000 

 to 700 specimens of Fteromalus puparum from a single chrysalis of one 

 of the larger butterflies. 



No observations have been made bearing upon the number of eggs 

 laid upon the host by the i)arent parasite, and just how far the mother 

 grades the number of eggs laid to the size of the host-insect is unknown. 

 The probabilities are that she does regulate her oviposition in this wny, 

 but it is also probable that she somewhat overstocks each host, as Poul- 

 ton lias observed thelchneumouidPaniscws cephalotes to do with Dicra- 

 nura vinula and other large European larvae (Trans. Eut. Soc. Lond. 

 188C, p. 1C2). A complication arises when we come to consider the very 

 few cases of a very small chalcidid attacking a large host insect. I say 

 the " very few cases," for it is a fact that as a rule these parasites do not 

 attack insects which they can not completely stock with their egg sup- 

 l)ly. Witli the case of the genus Gopidosoma, however, the parasite is 

 exceedingly' small and many of the host insects are large, as PlHsia ami 

 other large noctuids. As just stated, over 2,500 s[)ecimens of Gopido- 

 soma iruncatellnm liave been reared from one larva of Flusia hrassica', 

 and the eggs from which these parasites came must have been laid by 

 several females, as in no case have I been able to count over 100 eggs 

 in the ovaries of a Gopidosoma. It is true that my methods of making 

 this count have been rough. I have simply crushed the abdonren of 

 living individuals under a cover glass in glycerine and forced out the 

 ovaries under pressure, counting the eggs by means of the coiirdiimted 

 eye piece micrometer; but judging froui my experience with the ovaries 

 of larger insects, I have probably counted at least half. Probably, then, 

 seven or eight females oviposited in this one Plusia larva, and also at 

 the same time, as all larvae developed together, and transformed 

 together, and issued nearly together. 



