26 HOURS OF INSECTS. [CHAP. i. 



being open by day ; and on the other hand, that those 

 which are fertilised by bees would gain nothing by 

 being open at night. Nay, it would be a distinct dis- 

 advantage, because it would render them liable to be 

 robbed of their honey and pollen, by insects which 

 are not capable of fertilising them. I would venture 

 to suggest, then, that the closing of flowers may 

 have reference to the habits of insects, and it may be 

 observed also in support of this that wind-fertilised 

 flowers do not sleep ; and that some of those flowers 

 which attract insects by smell, emit their scent 

 at particular hours ; thus, Hesperis tnatronalis and 

 Lychnis vespertina smell in the evening, and Orchis 

 bifolia is particularly sweet at night. 



Bees appear, moreover, to be skilful in adapting the 

 hour of their visits to the habits of the plants. Thus 

 M. Boissier tells us (" Les Nectaires," p. 166), that he 

 observed some species of Sempervivum (S. tectorum* 

 S. arachnoideum, S. montanum, S. reflexum, and 5. 

 maximum] growing abundantly on rocks, which 

 secreted honey in the morning only. These plants 

 were much frequented by bees up to midday, but 

 quite deserted in the afternoon. He has also ob- 

 served that some bees which specially frequented 

 Limes and a field of Clover (Trifolium repens\ 

 went to the former in the early morning, and did 

 not commence visiting the clover until the dew was 

 off. During the height of summer in Provence, the 

 flowers, he tells us, secrete no honey in the heat of the 

 day ; and the bees also remain at home. Mr. Todd even 

 assures us that at Blidah in Algeria the bees during 

 summer do not work after eight in the morning. 



