416 INSECT ARCHITECTURE. 



deeper into the flesh, sometimes causing fatal inflam- 

 mations. 



Grub Parasite in the Snail. 



During the summer of 1829, we discovered in the 

 hole of a garden-post, at Blackheath, one of the 

 larger grey snail shells {Helix aspersa, Muller,) 

 with three white soft-bodied grubs, burrowing in the 

 body of the snail. They evidently, from their appear- 

 ance, belonged to some species of beetle, and we 

 carefully preserved them in order to watch their 

 economy. It appeared to us that they had attacked 

 the snail in its strong hold, while it was laid up tor- 

 pid for the winter ; for more than half of the body 

 was already devoured. They constructed for them- 

 selves little cells attached to the inside of the shell, 

 and composed of a sort of fibrous matter, having no 

 distant resemblance to shag tobacco, both in form 

 and smell, and which could be nothing else than the 

 remains of the snail's body. Soon after we took 

 them, appearing to have devoured all that remained 

 of the poor snail, we furnished them with another, 

 which they devoured in the same manner. They 

 formed a cocoon of the same fibrous materials during 

 the autumn, and in the end of October appeared in 

 their perfect form, turning out to be the Drilus jla- 

 vexcens, the grub of which was first discovered in 

 France in 1824. The time of their appearance, it 

 may be remarked, coincides with the period when 

 snails become torpid.* 



In the following autumn we found a shell of the 

 same species with a small pupa-shaped egg deposited 

 on the lid. From this a caterpillar was hatched, which 

 subsequently devoured the snail, spun a cocoon within 

 the shell, and was transformed into a small moth (of 

 which we have not ascertained the species) in the 

 spring of 1830. 



* J. It. 



