268 THE ENTOxMOX^OGISt's RECORD. 



Hibernation of Cataclysta lemnalis, L. 



By T. A. CHAPMAN, M.D., F.Z.S., F.E.S. 



My observations on this species, made in 1904, and reported in the 

 Entoiiiologist for 1905, dealt with the history of this insect in the 

 summer and in captivity. They showed that under such conditions 

 the species is really double-brooded, and lent much probability to the 

 idea that it is so naturally. Buckler's observations do not show in 

 what instars he had the larvae, but he had them in winter from 

 November 10th onward. He also says, that a larva figured in 

 November was | of an inch long, and must therefore have been in 

 the 3rd instar. He also says that they shut themselves in their 

 cases and hibernated from early in December until the beginning of 

 March. This implies that they hibernated in the third instar. 



This winter, somewhere about the end of December, I brought 

 home some duckweed with no thought of ('. leinnalu, but after a week 

 or two some cases amongst it attracted my attention, and were seen to 

 be those of ('. lemnalis. Unfortunately I paid no particular attention 

 to them, and they are now (February 25th) well grown, some in the 

 last instar (indoors). 



I have just brought home some more duckweed in hopes it may 

 not be too late to ascertain the hibernating stage. The larvae found 

 at this date had, however, been active and feeding, as seen by fresh 

 fronds of Loiina on their cases, and green contents in their priuiae doe. 

 One of these larvae appears to be in the second instar, the remainder 

 are in the third. This winter has been a very open one, green duck- 

 weed was present all the winter. It often in a hard winter practically 

 disappears. The i\ lemnalis has probably been able, therefore, to feed 

 a little all the winter. Along with them were certain smaller cases, 

 old and empty. I am inclined to think that these have been abandoned 

 by larvte that hibernated in them in the second instar, and left them 

 to make new cases on entering the third stage. 



Having left it till late before noting the larval stage, I am unable 

 to say positively what is the hibernating instar, it may be apparently 

 the second, or perchance the third, I rather incline to the former view, 

 or it may be'either as the season determines. One thing is clear, that 

 in an open winter, with plenty of good duckvveed obtainable all the 

 time, the larv* begin to feed in February, and probably do a little 

 feeding all winter. The dead cases observed may of course not be 

 abandoned by larvie that have made new ones, but the cases of larvte 

 that have died, been eaten by enemies, etc. I have not seen a larva 

 make a totally new case in captivity, but they sometimes do what is 

 much the same, the larger case is made by lengthening the old one and 

 a portion of the smaller diameter sometimes becomes detached. The 

 empty cases found were, however , the whole case not such a detached 

 portion. 



A portion of duckweed brought home in December, or later, enough 

 to float over the surface of a small basin, afi'ords from half a dozen to 

 a dozen cases, so there should be no difficulty in findiog out in another 

 season which is really the hibernating stage of the species. Of course, 

 it must be from a pond where ' '. lemnalis occurs, and it is of course 

 more certainly productive when the total amount of weed is reduced to 

 a twentieth of its final autumnal area, so that the larvjiB are no doubt con- 

 centrated. What becomes of tlielarva? in a severe winterwhen the Leiinia 

 is apparently annihilated is another question also worth looking into. 



