86 THE EEPORT OF THE No. 36 



emergence boxes in the field, sufficient material was not obtained and the data 

 were got from a limited number which were bred in the lalxiratory. These com- 

 menced to deposit eggs on July 20th, probably very much later than would be the 

 (!ase in the field. Under laboratory conditions the weevils are somewhat retarded 

 and do not prove as healthy as those in the field. The vials were examined and 

 the eggs counted every four days. The maximum number of eggs laid by an 

 individual in this experiment was 249 and the minimum 73, while the average 

 was 154, all deposited within a period of six weeks. Thus it will be seen that there 

 are two broods depositing eggs simultaneously. In the case of both broods ovi- 

 position ceased at the same time this year but in last year's experiments many 

 weevils continued to lay until the middle of September. Endeavour will be made 

 another season to determine whether the same weevils oviposit twice. In no single 

 instance as yet have I discovered weevils of the summer brood that did not lay 

 eggs and therefore I assume that a proportion of the summer brood does not die 

 but after ovipositing hibernates, and in the spring, after a period spent in 

 feeding and development, oviposits again. If this is not the case, it is difficult 

 to account for the origin of the numerous overwintered individuals. 



Paethenogenesis, In all the experiments conducted here no male weevils 

 have been discovered. Although about 300 specimens have been examined and 

 dissected only those have been found possessing the genitalia proper to the female. 

 Also among the large number kept in confinement none were ever found in copula- 

 tion; neither has it been observed in the field. Consequently the belief has been 

 held by us for some time that 0. ovatus is parthenogenetic. This impression was 

 strengthened by the recent discovery in France by J. Feytaud* that 0. sulcatiis, 

 its near ally, was parthenogenetic, making the fourth Coleopteron known in which 

 the method of reproduction is by parthenogenesis. To test the matter a number 

 of pupae were collected in the field this season and isolated in vials. On reaching 

 adult condition they were placed each in a glass vial loosely stoppered with cotton 

 wrapped round with paper, and fed on strawberry leaves. The vials were kept in 

 my house and examined at intervals of two or three days. At first cotton wool 

 was used for vial stoppers but it was found that the weevils deposited eggs among 

 the wool, making them very difficult to find. When the wool Avas wrapped in paper 

 the difficulty was surmounted, although the beetles would occasionally deposit eggs 

 in a fold of the paper. Oviposition commenced on July 20th and continued until 

 August 30th. The eggs of each individual were kept separate. On August 34th 

 larvae were found to have hatched from eggs laid by weevil No. 5 and within a 

 few days larvae were also found in the other vials. Thus it appears evident that 

 the weevil is parthenogenetic. 0. ovatus thus makes the fifth coleopteron known 

 to be parthenogenetic the others being 0. turm. Bohem, 0. cribricollis Oyll, A. 

 ligustici Linn., and 0. sulcatus Fabr. Some individuals produced a larger propor- 

 tion of infertile eggs than others, and it may be noted that twenty days elapsed 

 between the time when the first food was given and the commencement of oviposi- 

 tion. This is a greater period than would occur in nature and in the experiments 

 conducted by Treherne- the minimum period was found to be eight days. T 

 attribute the difference to confinement and artificial conditions of feeding. 



Incubation and Fertility. Experiments made to find the period of incuba- 

 tion showed that it varied from sixteen to twenty-two days. 



The fertility of the eggs varied from 68 per cent, in the case of those laid 

 by overwintered adults to 80 per cent. \n the case of those laid by the summer 

 brood. 



