196 F. W. DRY. 



no food, but a pad of cotton-wool was kept moist in the glass tube, which was closed 

 with a dry pad of cotton- wool ; {g) the Antestia eggs used had been deposited in the 

 laboratory, and so kept as to prevent their accidental parasitisation ; {h) none of the 

 eggs showed eye-spots when given to the parasites ; {i) the number of eggs in each 

 experiment was 50 ; when the experiment started eggs to this number were placed 

 in a little cork tray having a rough floor so that the eggs would not roll about. 



The results obtained from a series of ten experiments in which the above conditions 

 were observed were as follows : — 



(a) The average lifetime of the parent parasites was 6 days, 8 days being the 

 maximum. 



{b) On the average a little longer than 10 days elapsed before the first egg became 

 blue, and between 13 and 14 days before the last one to become blue had 

 changed ; it will thus be noticed that the time from parasitisation of the 

 egg to its going blue was about a third of the time from parasitisation to 

 emergence of the parasite. 



(c) The average time between the mating of the parasites and the first hatching 

 of their progeny was 31 days. 



[d) The total number of offspring obtained from the ten females was 233, or an 

 average of a little over 23 per female ; 256 eggs went blue, but 23 did not 

 produce parasites ; the highest number of offspring from one female was 34. 



{e) Of the 233 parasites thus obtained the numbers of the sexes were : — Male, 43 ; 

 female, 190. 



(3) Proportions of the Sexes. 



At the same time as the series just described other experiments with mated 

 females, not fed but given water, were carried out in which one or more of the con- 

 ditions were not the same as those defined above. Particulars of some of these will 

 be given directly. The times obtained were not dissimilar from those just recorded, 

 and need not be given, but these other experiments give a larger number of parasites 

 reared in the laboratory from mated parents from which to calculate the proportions 

 of the sexes. 



In 41 experiments, including the ten of the series just described, the numbers 

 of the sexes were: — Male, 178; female, 696. The percentages were thus almost 

 exactly :— Male, 20 per cent. ; female, 80 per cent. 



In every one of these 41 experiments the number of females exceeded the number 

 of males. In one experiment only all the offspring, 34 in number, were female. 

 In that experiment the parent male was the offspring of a virgin female. In six 

 other experiments in which the parent males were bred from virgin mothers the 

 offspring, totalling 31 males and 89 females, always included both sexes. 



(4) One Male mating with several Females. 



It was found that males will readily mate with several females. Mating, for 

 both species of parasites, is an affair of seconds. Occasionally a male would mate 

 twice with one female in rapid succession, but very often, and this applies also to 

 Telenomus, I noticed that a female which had been mated would run away from or 

 resist further attentions from the male. 



One Hadronotus male, which emerged from a coffee bug egg on 30.xii.l917 and 

 was never given food or drink, and died on 4. i. 1918, mated during the course of his 

 life with 16 virgin females. These 16 were all that were available ; with the first 

 two he mated twice, with the others once. These females were kept away from all 

 other males for the remainder of their lives, being kept singly in tubes, provided with 

 water, and supplied with eggs ; 369 parasites were in all bred from them, 68 male, 

 and 301 female. In every instance the number of females exceeded the number of 

 males. 



