166 Mr. W. B. Pickering's Observations on 



Having been informed by my friend Mr. G. Waterhouse that 

 many of the Andrence were to be obtained during the winter months 

 by digging, and as this mode of collecting presented several ad- 

 vantages, such as the discovery of the sexes of these bees, the as- 

 certaining of the insects parasitic on the Andrence, and also that the 

 specimens so obtained would be in the greatest state of perfection, 

 I determined to adopt it, and I was fortunate in capturing An- 

 drena Clarkella, A. tibialis, (both sexes of each,) and some species 

 of Halictus and Sphecodes on Christmas-day ; in the evening I 

 killed these insects, and on examining a specimen of .^. tibialis prior 

 to setting it out, I observed some protuberances between the abdomi- 

 nal segments, and thinking my bee might be stylopized I endeavoured 

 to remove one of these swellings, and the Society may imagine my 

 surprise and joy on seeing a perfect Stylops issue forth. 



That the Andrena from which the Stylops was taken had never 

 quitted its cell is proved by the state of the specimen, which is very 

 perfect, the discharge of a white fluid (this happened while the bee 

 was in my hand), which takes place shortly after the birth of every 

 insect ; and from its being in its cell. It may be objected that the 

 fact which I have noticed involves no new idea as to the economy 

 of these insects, and that in finding a Stylops within the body of a 

 perfect bee, I have done no more than many other collectors of in- 

 sects ; but in opposition to this I would state that the bees hitherto ob- 

 served to be stylopized by every author have been found at large, 

 and consequently that there is no proof as concerns them that the 

 eggs of the Stylops have not been deposited in their bodies after 

 their escape from the cells. The reverse of this however is the case 

 with my discovery. Many of the Andrence are known to appear on 

 the first bursting forth of the palm blossoms, a circumstance neces- 

 sarily dependent on the weather ; and as these trees afford an abun- 

 dant supply of pollen, I consider it is in order to avail themselves of 

 this supply that they undergo their last change so long previous to 

 their appearance on the wing. 



Admitting then the fact that our bee had never quitted its cell, 

 and the Stylops ready to burst forth from an inclosed bee, — knowing 

 moreover that the Andrence in their imperfect states inhabit earthen 

 cells formed by their parents, which are closed when the e^^ and a 

 sufficient supply of pollen paste are stored up,and that theStylops from 

 its delicate structure is unable to make its way through any depth 

 of earth (for it was at about the distance of a foot that I found the 

 cells of the Andrena), — we at once arrive at the conclusion that the 

 Stylops must lay its egg previous to the closing of the bee's cell. 



There is also another circumstance which has been overlooked by 



