RILEY — SARRACENIA INSECTS. 235 



Descriptions and Natural History of two Insects -which 



brave the Dangers of Sarracenia variolaris. 



By Chas. v. Riley, M.A., Ph. D. 



Renewed interest has lately been manifested in the insect- 

 catching attributes of various plants, and especially of Dionaea, 

 Drosera, Nepenthes, Darlingtonia and Sarracenia, and some 

 important additions to our knowledge of the functions of these 

 plants have been made — additions largely due to the exertions 

 of Mr. Darwin, who is understood to be preparing a work on the 

 subject of "Insectivorous Plants." Sarracenia variolaris^ more 

 particularly, has been the subject of careful and thorough obser- 

 vation and experiment on the part of Dr. J. H. Mellichamp of 

 Blufflon, S. C, through whose kindness and that of Mr. H. W. 

 Ravenel of Aiken, S. C, I have been enabled to study the insects 

 associated with the plant. 



The leaf of Sarracenia is, briefly, a trumpet-shaped tube 

 representing the petiole and having a broad ventral wing, with a 

 hood or lid covering more or less completely the mouth. The 

 inside wall is so furnished that most insects entering the tube 

 are prevented from issuing again. From the mouth to about 

 midway to the bottom it consists of a dense, velvety pubescence 

 which is quite slippery, especially as the finger passes over it in 

 a downward direction, and effectually prevents most insects from 

 scaling the tube. From midway downward the surface is beset 

 with retrorse bristles which gradually increase in size till within 

 a short distance of the bottom, where they suddenly cease and the 

 surface is smooth. Similar bristles are also found under the hood. 

 It had long been known that insects were caught in these tubes 

 in large quantities, and were drowned and macerated in a fluid 

 which gathered at the bottom. Dr. Mellichamp has now settled 

 beyond dispute that the fluid — which is a pure secretion, and not 

 the result of dew or rain, as it partly may be in some of the spe- 

 cies of Sarracenia with more open lids — has toxic and solvent 

 properties ; and that not only is honey secreted in numerous drops 

 around the inside of the mouth, but that there is actually a trail 

 of it, when the leaf is in fullest vigor, running down the margin 

 of the wing to the ground — the whole forming a most eflfectual lure 

 to honey-loving insects. 



