242 HUMBLE-BEES. 



rich yellow ; when it grows old, especially the male, 

 exchanges these brilliant colours for a cinereous hue, 

 which circumstance misled Fahricius to give it as a 

 distinct species, under the name of A. Senilis. But 

 not only yellow and red, hut even black and white 

 hairs are apt to change their colours through age. 

 All these circumstances make it a matter of some 

 importance to be able to distinguish a recent insect 

 from one that has been long disclosed. This may 

 often be done by inspecting the state of its wings, 

 for in the latter, especially in males, they are usually 

 lacerate at the apex ; the body, too, has frequently 

 a good deal of its hair rubbed off. It will not be 

 without use to know into what the predominant 

 colours fade ; yellow will usually first turn pale, and 

 then cinereous ; red will turn through tawny to yel- 

 low, and sometimes to cinereous ; white will turn to 

 pale, and sometimes to tawny ; and black will now 

 and then turn white. But this is not all the difficulty 

 with which the describer of the Bombinatriees has 

 io struggle ; the males in general resemble the fe- 

 males sufficiently to be known as such ; but there 

 are several so unlike them as to be easily mistaken 

 for different species ; and I am by no means certain 

 that I have not, in more instances than one, described 

 the sexes under different names. Till all can be 

 traced to their nidi, this is not easily to be avoided-" 

 We shall now proceed to give examples of the 

 two genera Bombus and Apathus. 



