The Glow-Worm and Other Beetles 



which suddenly, at a given moment, irre- 

 sistibly commands an obscure grub to aban- 

 don the retreat in which it enjoys security, in 

 order to make its way through a thousand 

 difficulties and to reach the light, which would 

 be fatal to it on any other occasion, but which 

 is necessary to the perfect insect, which could 

 not reach it by its own efforts. 



But the layer of Osmia-cells has been re- 

 moved; and the pick now reaches the Antho- 

 phora's cells. Among these cells are some 

 which contain larvae and which result from 

 the labours of last May; others, though of 

 the same date, are already occupied by the 

 perfect insect. The precocity of metamor- 

 phosis varies from one larva to another; 

 however, a few days' difference of age is 

 enough to explain these inequalities of de- 

 velopment. Other cells, as numerous as the 

 first, contain a parasitical Hymenopteron, a 

 Melecta (M. armata), likewise in the per- 

 fect state. Lastly, there are some, indeed 

 many, which contain a singular egg-shaped 

 shell, divided into segments with projecting 

 breathing-pores. This shell is extremely thin 

 and fragile; it is amber-coloured and so 

 transparent that one can distinguish quite 

 plainly, through its sides, an adult Sitaris 

 (S. humeralis), who occupies the interior and 

 36 



