Bramble-bees and Others 



ing them and ascertaining the sex of the Os- 

 mia Inside, let us wait for the transformation 

 Into the perfect insect, which will take place 

 towards the end of summer. If Impatience 

 gets the better of us, we can open them at the 

 end of July or in August. The Insect is then 

 In the nymphal stage ; and it Is easy, under this 

 form, to distinguish the two sexes by the 

 length of the antennae, which are larger In the 

 males, and by the glassy protuberances on the 

 forehead, the sign of the future armour of 

 the females. Well, the small cocoons, those 

 in the narrow front cells, with their scanty 

 store of provisions, all belong to males; the 

 big cocoons, those in the spacious and well- 

 stocked cells at the back, all belong to females. 



The conclusion is definite : the laying of the 

 Three-horned Osmia consists of two distinct 

 groups, first a group of females and then a 

 group of males. 



With my pan-pipe apparatus displayed on 

 the walls of my enclosure and with old hur- 

 dle-reeds left lying flat out of doors, I ob- 

 tained the Horned Osmia In fair quantities. 

 I peisuaded Latreille's Osmia to build her 

 nest in reeds, which she did with a zeal which 

 I was far from expecting. All that I had to 



io8 



