NOTES ON THE GENUS CERUBA (dICRANURA). 139' 



Notes on the genus Cerura (Dicranura). 



(Eev.) a. miles moss, m.a. 



Having spent a considerable amount of time during March in 

 searching for the cocoons of the three " kittens," I have thought that 

 the following notes may perhaps be of interest to others. My efforts 

 have resulted in the finding of a large number of empty cocoons and some 

 full ones, and, by dint of perseverance, I have, for the first time in my 

 life, had all four British Dicranurid species represented at the same 

 time by living pupaj. Let me at once assert that nothing short of the 

 spirit of the raving enthusiast will accomplish this feat ! But if the 

 work was laborious it has been none the less of absorbing interest. 



My first conclusion is that this is undoubtedly the wrong time of 

 year to secure the best results, and I am led to believe that such is 

 especially the case in any part of the country where insectivorous birds 

 are numerous. Let me tabulate my observations under the headings 

 of the four species : — 



Centra vinitla. — The species is, of course, common throughout 

 Norfolk, but comparatively few cocoons have been found, as the larvte 

 very frequently leave the tree. The cocoons were generally near the 

 ground, but occasionally six or eight feet up the trunk, and on all 

 sides of the tree. They are fairly easy to detect as they usually 

 protrude above the general level of the surrounding bark. Several 

 fresh cocoons had been pecked open by birds and the contents cleared. 

 This is also largely the case with Trochilium ajyifoniiis at the roots of 

 poplar, the bark presumably being tapped in likely places until the thin 

 drumlike cover gives forth a hollow sound and betokens the presence of a 

 cocoon within. I only obtained one full cocoon of C. vinitla, from 

 which a large female has already emerged after barely three weeks of 

 moderate forcing in a kitchen cupboard. 



Centra fiircitla. — Of this species I have some fourteen full cocoons, 

 but these were all obtained in the larval condition last autumn, some 

 in the Lake District near Windermere, and some in the Norfolk 

 Broads. C. ftirctila seems equally common in both districts, and, while 

 a few specimens fell in the beating-tray, I obtained the majority of 

 larvfB by searching small sallow-bushes. In such cases, where the 

 stems are smooth and thin, they, as a rule, undoubtedly leave the bush 

 before pupation. Their characteristic method of entirely stripping the 

 end of a small bough, and the nature of the frass, frequently testify to 

 their recent presence, but I can only recall two instances of the 

 discovery of their cocoons in such unprotected positions, and these 

 were probably cases of necessity, the bush having stood in water and 

 thus prevented their escape. I have recently found a considerable 

 number of C fnrcula cocoons on willow trunks near Norwich. A few 

 of these have been freshly emptied by bu'ds, but the majority were old. 

 The most favoured spot for pupation, where, indeed, they are most 

 protected and easiest to see, is underneath pieces of bark that have 

 lifted and can be broken off with a trowel. C. fnrcula seems to 

 affect any species of willow without much preference, and the cocoon 

 occurs on every side of the tree, and in almost any position, provided 

 that it be dry. 



Centra bijida. — This species, somewhat rare in the north, seems 

 common in the eastern counties, judging from the large number of 

 June 15th, 1905. 



