October, 1S771 9^ 



NATUEAL HISTORY OF HYDROCAMPA STAGNALIS. 

 BY WILLIAM BUCKLER. 



Wheu I was investigating the early stages o£ the other species of 

 HydvocampidcB with aquatic larvse, I had been foiled with stagnalis, 

 but, in the early summer of 1876, I was fortunate enough to find a 

 kind and enthusiastic helper in Mr. W. R. Jeffrey, of Ashford, and 

 by the aid he rendered me ^I am now able to give a full account of 

 this sjiecies throughout. 



In Stainton's Manual, the larva is counted among the unknowns ; 

 Guenee says nothing about it ; but from the synonymy of the species, 

 potamogaJis, Hb., being one of its names*, it would appear that 

 Potamogeton had passed for its food, and Dr. E. Hofmann says that 

 0. Hofmann found it in cases made of the leaves of that plant. But 

 this notion had been driven out of my head by the result of many 

 attempts to find the larva in such a situation, and I had come to sus- 

 pect that Sparganium would prove to be the right food, a suspicion 

 now strengthened into certainty, as will be seen by what follows. 



Mr. Jeffrey began by sending me specimens of every sort of case 

 he could find tenanted by aquatic larvae, and sti'ange and interesting 

 enough many of them were ; and each fresh form was hailed as the 

 desideratum, till the appearance of the imago dispelled our hopes ; at 

 last, on July 18th, he bred a specimen of stagnalis from one of three 

 pupa-cases, all alike fastened to pieces of Sparganium, which he had 

 found in a brook : this gave us encouragement ; but, though we most 

 carefully scrutinized again all the cases that had been found, we could 

 detect none like these little pouches, from one of which stagnalis had 

 emerged. 



Then it occurred to my friend, by this time feeling nearly confi- 

 dent that I had been right in saying that Sparganium would in all 

 likelihood prove the true food, to capture several moths of both sexes, 

 and confiue them in a vessel, at the bottom of which he had arranged 

 pieces of Sparganium both fioating on water and standing erect ; this he 

 did on July 21st, and seeing that by the 27th, all the moths were dead, 

 he examined the pieces of the plant, and on the underside of one of the 

 floating pieces found two neat little batches of eggs, and forwarded 

 them to me. The larvse hatched on August 5th and 6th, and imme- 

 diately on quitting the egg-shells began to eat their way into some 

 fresh pieces of Sparganium simplex, which I had ready prepared, and 

 when inside the rind mined the pith of the plant in a longitudinal direc- 



* In Staudinger and Wocke's Catalogue. 



