126 Insect Architecture. 



PROPOLIS. 



Wax is not the only material employed by bees in their 

 architecture. Beside this, they make use of a brown, odo- 

 riferous, resinous substance, called propolis* more tenacious 

 and extensible than wax, and well adapted for cementing and 

 varnishing. It was strongly suspected by Reaumur that the 

 bees collected the propolis from those trees which are known 

 to produce a similar gummy resin, such as the poplar, the 

 birch, and the willow ; but he was thrown into doubt by not 

 being able to detect the bees in the act of procuring it, and 

 by observing them to collect it where none of those trees, nor 

 any other of the same description, grew. His bees also 

 refused to make use of bitumen, and other resinous sub- 

 stances, with which he supplied them, though Mr. Knight, as 

 we shall afterwards see, was more successful.| 



Long before the time of Reaumur, however, Mouffet, in 

 his Insectarum Theatrum, quotes Cordus for the opinion that 

 propolis is collected from the buds of trees, such as the 

 poplar and birch ; and Reim says it is collected from the 

 pine and fir. J Huber at length set the question at rest ; and 

 his experiments and observations are so interesting, that we 

 shall give them in his own words : 



" For many years," says he, " I had fruitlessly endeavoured 

 to find them on trees producing an analogous substance, 

 though multitudes had been seen returning laden with it. 



" In July, some branches of the wild poplar, which had 

 been cut since spring, with very large buds, full of a reddish, 

 viscous, odoriferous matter, were brought to me, and I planted 

 them in vessels before hives, in the way of the bees going 

 out to forage, so that they could not be insensible of their 

 presence. Within a quarter of an hour, they were visited by 

 a bee, which separating the sheath of a bud with its teeth, 



* From two Greek words irpo TTO\IS meaning before the city, as the sub- 

 stance is principally applied to the projecting parts of the hive, 

 f Phil. Trans, for 1807, p. 242. 

 I Schirach, Hist, des Abeilles, p. 241. 



