NOTES ON THE EARLY STAG-ES OF CEMIOSTOMA LABURNELLA. 185 



The beautiful imagines of Ceuiinstoma labnrnella may often be seen 

 in abundance in May and again in August in the close neighbourhood 

 of laburnum trees. They are fond of resting on the leaves and fly out of 

 the foliage, when that is disturbed, like a crowd of minute snow 

 flakes. I think the period during which the imagines of either brood 

 are on the wing lasts about six weeks. As far as my observations go 

 I know there are two distinct broods in Chiswick, the moths occurring 

 in May and again, generally much more numerously, in August, 

 while the larvfe may be found in June, July and again in September. 

 I think It quite possible that from the end of April till the beginning 

 of October imagines might be taken on the wing and that full fed 

 larvi^ might be found any time from June till November, but I cannot 

 consider this species as being continuously brooded during the summer, 

 as some have suggested. I think that the last stragglers of the first 

 brood are sometimes overtaken by the forwards of the second brood, 

 and the two following facts seem to point distinctly to the truth of 

 there being only two broods during the year ; firstly, there are two 

 periods in the year when the imagines, on the one hand, and, two 

 periods when the larvte on the other, are abundant, and secondly, that 

 between these periods of abundance the imagines and the larvm 

 respectively are very scarce. 



Hibernation takes place in the pupal stage, thus this species 

 differs in this respect from its very close ally, C. ftpartifolidla, which 

 passes the winter as a larva, and which has only a single brood in the 

 year. 



To me one of the most interesting observations I made on 

 C. labnrnella, was that Avith regard to the supposed habit of the larva 

 of letting itself down from the trees when ready to spin its cocoon. 

 I have alread}^ stated that the full fed larva of the autumn brood after 

 leaving its mine, crawls down the stem of the tree. In so doing, it 

 would doubtlessly spin up in any suitable situation on the bark that it 

 might find. If no such situation is found, the larva wanders over the 

 ground below the tree. Instead of making a long peregrination over 

 the branches and down the trunk of the tree, how much more simple, 

 how much less laborious it would be for the larva to lower itself, by 

 means of a thread of silk, straight as a plumb line to the earth ! 

 Therefore, because this seems so natural and so plausible, we think we 

 have seen the larvae letting themselves down in hundreds. We have 

 certainly seen hundreds of larvte actually hanging by threads, we have 

 seen many actually let themselves down off the tree. They do not 

 however take this action voluntarily. It is the force of circumstances 

 that compels them to do so. When we see them hanging by threads 

 we shall, if we closely examine them without scaring them, discover, 

 not that they are letting themselves down, but that they are all actually 

 trying to get up, to regain the position from which they have fallen. 

 I tir:st noticed this on September 20th, 1908, when I saw six larvfe 

 hanging on threads and found that they were all trying to ascend, 

 and that they had little balls of silk between their thoracic legs, show- 

 mg how they rolled up the silk as they reascended. I then saw some 

 larvae fall suddenly off the branches and hang by a thread about a foot 

 long, but after a short time they also began climbing up again. By a 

 sudden side movement of the head and thorax, the larva is able by 



