9 ^1 ) [NovemVier, 



slioni. On the anal segment is a very peculiar striictni-e (fig. 2) — a pair 

 of decurved spines or spurs, and at the base of each is a spiracle. The 

 use of these singular appendages is very interesting, as stated in Prof. 

 Miall's " Natural History of Aquatic Insects," p. 94, in his remarks on 

 the larva of Don acta, which is very similar in hal^its and structure to 

 that of Hcvmonia : — " Eoots of NymjJuea frequented by Bonacia were 

 observed by Schniidt-Sehwedt* to exhibit peculiar scars. These were 

 discovered with difficulty, owing to the darlc colour and uneven surface 

 of the roots. There was in each case a rough hole, made apparently by 

 the jaws of the larva when feeding, and. at a distance corresponding with 

 the length of the body, a pair of small slits. On microscopic examination, 

 these slits were found to penetrate the epidermis of the roots. Some- 

 thing of this had been previously observed by Siebold, who in 1859 

 described the larva as biting a hole in the roots of Sparganium, pass- 

 ing the end of the aJidomen into it, pressing the spiracles by the help 

 of the curved spines close against the hole, and so drawing the contained 

 air into its body. Schmidt-Schwedt Itelieves that the pair of openings 

 are made not l)y the mouth Ijut l)y the spines, and that the air is 

 drawn in by internal channels running along them."t 



MacGrillivi'ay, in his paper on " Aquatic ChrysomeU(hv,"X states 

 that the larva of [Hivmonia nigrlcornls, Kirby] can be recognized from 

 that of Bonacia by having the sixtli and seventh alidominal tergites 

 each armed with a double row of setae, most of which are twice as long 

 as those found on the other tergites, and the supra- sj)iracular setae 

 wanting. 



The cocoon (fig. 3) is sulx-yliudrical, obtuse-ended, semitrans- 

 parent, smooth and glassy looking, varying in colour from yellowish 

 brown to darker brown. When the beetle is mature, its markings can 

 plainly be seen through the semitransparent walls of the cocoon. The 

 usual place of attachment is to the stems of the food-plant, a few inches 

 above the roots, there being sometimes three or four cocoons on a stem. 

 I have also f ovmd them at the roots spun up among the suckers. I am 

 indebted to Commander J. J. Walker for the accurate drawings by 

 Miss M. A. Sharp of the larva, breathing apparatus, and cocoon. 



Oxford: Octoher 6th, 1911. 



' Berl. Eiitoia. Zeitsclir., xxxi, pp. 325-334, Taf. v, figs. Ml (1887). 



t Dewitz (Berl. Entom. Zeltschr., xxxii, p. 5, 1888) believes that in Hcemonia, and pre- 

 suma1)ly in Douacia also, the spiracles serve for admission of air to the body as Siebold main- 

 tained. Sehmidt-Schwedt has, H.E.Z., 1880, reaffirmed his original statement. 



{ Bull, N. York State Museum, 08, Entom. 18, p. 3H (1903). 



