290 INDIRECT BENEFITS DERIVED FROM INSECTS. 



second class includes those which entrap them by some 

 viscosity of the plant, as many species of Rhododendron, 

 Kalmia, Robinia, Silene, Lythrum, Populus balsamifera, 

 &c. c And under the third class will arrange those which 

 ensnare by their leaves, whether from some irritability in 

 them, as in Dioncea, Drosera, &c, or merely from their 

 forming hollow vessels containing water, into which the 

 flies are enticed either by their carrion-like odour, or the 

 sweet fluid which many of them secrete near the faux, 

 as in Sarracenia, Nepenthes, Aquarium, &c, the tubular 

 leaves of which are usually found stored with putrefying 

 insects. In this last class may be placed the common Di- 

 psacus of this country, the connate leaves of which form a 

 kind of basin round the stem, that retains rain-water in 

 which many insects are drowned. To these a fourth class 

 might be added, consisting of those plants whose flowers 

 smelling like carrion (Stapelia hirsuta, &c.) entice flies to 

 lay their eggs upon them, which thus perish. 



The number of insects thus destroyed is prodigious. 

 It is scarcely possible to find a flower of the Muscicapce 

 Asclepiadece that has not entrapped its victim, and some 

 of them in the United States closely cover hundreds of 

 acres together. 



What may be the precise use of this faculty is not so 

 apparent. Dr. Barton doubts whether the flowers that 

 catch insects, being only temporary organs, can derive 



c Small flies are sometimes found sticking to the glutinous stigma 

 of some of the Orchidea; like birds on a limed twig : (Sprengel Ent- 

 decktes Geheimniss, 21— ) and ants are not unfrequently detained in 

 the milky juice which the touch of even their light feet causes to 

 exude from the calyxes of the common garden lettuce. Ann of Bot 

 ii. 590. ' J 



