Sarracenia adunca to entrap Insects, | 51 
suitable to its purpose ; then hanging its posterior extremity over 
the margin, it ejected on the internal surface of the tube a larva 
with a black head, which immediately proceeded downwards by 
a brisk vermicular motion. This viviparous musca was more than 
double the size of the common house-fly, had a reddish head, and 
the body hairy, and streaked grayish. I had often noticed it. be- 
fore among the S. adunce, but could never ascertain its object ; 
the hoods probably obstructing my view. | 3 
That insects may be found in these tubes which were not al- 
lured by the bait, I have well ascertained. At the time that 1- 
discovered the origin of the larvæ, I observed a beetle (Scarabeus 
carnifex, a herd being near) in its flight strike against the erect ap- 
pendage of the S. flava and fall into the tube. In the leaves of the 
S. adunca, growing on the margin of a large pool, I once observed 
the fragments of a large Gryllus and several Gyrini. These and 
similar appearances have led me to suspect that our large Nepa*, 
an extremely voracious insect, may occasionally use these tubes 
as storehouses. The hooked feet of this last insect would doubt- 
less enable it to ascend against the inverted pubescence. 
What purposes beneficial to the growth of these plants may be 
effected by the putrid masses of insects, I have never ascertained ; 
but I learn from a hint given in the article Dionæa, in Rees’s 
Cyclopedia, that it has been discovered that the air evolved is 
wholesome to the plants. I once entertained a suspicion that 
this air might be of such a deleterious nature as to cause the 
precipitation of thé insects exposed to it, but I have long since 
relinquished it as entirely groundless. 
* Very nearly allied to Nepa grandis of South America. It is very strong, and often 
destroys the Spring Frog. It inserts the claws of the two fore-feet into one of the frog's . 
hind legs, and with the claws of its hind feet it grapples rice-stubble, or some aquatic 
. plant; the frog unable to disengage itself becomes exhausted by struggling. 
n-2 ! The 
