Miscella n eous. 181 



On the Reproduction of Wasps. By M. Paul Marchal *. 



The results of my researches on the earth-burrowing wasps 

 ( Vespa gennanica, V. vulgaris) are as follows : — 



Their nests, when they are fully formed, contain two sorts of cells, 

 the small and the large. The latter always constitute the lower 

 part of the wasp's nest, for example the two lowest combs, while 

 the others make up the rest of the nest, namely the six to ten combs 

 superposed. 



The large cells, which are only built by the workers during the 

 first fortnight of August, may, at an early period, receive indif- 

 ferently either females or males, the former being either queens or 

 very large workers, the latter always in small proportion ; after- 

 wards, at the beginning of September, these cells are entirely set 

 apart for the queens to such an extent that in October only queens 

 are to be found in them, the males being entirely excluded. 



The small cells, on the contrary, from the time that the laying of 

 males has begun, contain indifferently up to the end of the season 

 either workers or males. 



The proportion of males in the combs of small cells decreases 

 from below upwards, with this remarkable exception — that if there 

 be a mixed comb containing at one and the same time large and 

 small cells, the small cells of the mixed comb are influenced by the 

 proximity of the large cells, and contain but a very small quantity 

 of males. 



The commencement of the period for laying males coincides 

 very nearly with the period of the appearance of the large cells and 

 takes place in the first fortnight of August. The curve which 

 represents their production rises suddenly in an almost vertical 

 manner to reach its maximum ; it then descends gradually, with or 

 without oscillations, to the end of the reproduction. 



The queen takes a prominent part in this great production of 

 males, because the laying workers have already long since disap- 

 peared, whilst the young male larvse are still to be found in great 

 numbers in the nests. 



The queen has then (at least after the early days of September) 

 the power to determine with certainty the female sex of the eggs 

 which she lays in the large cells ; on the other hand, she lays indiffe- 

 rently either female or male eggs in the small cells. 



One can only admit, in order to explain this remarkable fact, the 

 principle of the theory of Dzierzon, based upon the fecundation, 

 because if the production of males were due, for example, to some 

 influence of season, it is evident that the eggs laid at the same epoch 

 in the large cells would become male just as much as the others. 



In order to interpret all the facts, this theory ought nevertheless, 

 in my opinion, to be modified, by allowing the intervention of 

 another factor than the will of the queen. We will admit, then, 



* This work was carried out partly at the Entomological Station at 

 Paris. The experiments and observations on -which the conclusions 

 arrived at are based will be published in detail later. 



