7884 



Insects. 



Plumules in the Wings of the Genus Pieris. — At a late meeting of the Manchester 

 Literary and Philosophical Society Mr. John Watson read a paper " On certain Scales 

 of some Diurnal Lepidoptera," in which he recommends a new and careful study of 

 this subject. In some genera peculiar scales, called plumules, have long been known ; 

 but examination with the binocular microscope shows that they are not flat, like ordi- 

 nary scales, but cylindrical and hollow. They have been found only in certain genera 

 (named in the paper) at present, and on the males alone; they possess generic resem- 

 blances and specific differences, each species displaying its own distinguishing variety. 

 One of great beauty and novelty, found only on two African butterflies, Pieris Agathina 

 and P. Chloris, was described, and some very fine drawings of it, by Mr. Joseph Side- 

 botham, were exhibited, and also other figures by him of about one hundred species 

 never figured before. The names and habitats of the insects were given, and the author 

 pointed out the value of these scales for the assistance of the scientific entomologist in 

 arranging genera and species. He then entered into the question as to their probable 

 use as air-vessels in the economy of the insects possessing them. The chairman 

 remarked that the scales of the Lepidoptera may prove as valuable in determining 

 species as the scales of fishes. Mr. Sidebotham alluded to the value of the binocular 

 microscope in defining the cylindrical form of the plumules, and described the mode 

 of finding them in situ by breaking the wing. Mr. Watson slated that some of Mr. 

 Sidebotham's excellent drawings were taken under the eighth objective, magnifying 

 750 diameters. Mr. Watson further said that he had examined the wings of 400 spe- 

 cimens of the Papilionidae, but had not discovered any plumules in that family. He 

 also alluded to several so-called species from South America, of which no males have 

 yet been found, others of which no females have yet been discovered, and suggested 

 the possibility of some of these being male and female of the same species, to ascertain 

 which careful examination of the scales might be useful. Mr. Watson exhibited a 

 number of mounted specimens of the plumules, and four cases of the Lepidoptera, 

 from whose wings the ninety-eight drawings figured by Mr. Sidebotham were taken. 

 They were principally Pieris, Anthocharis, Euterpe and Eronia. Amongst the former 

 were some new and unnamed species from Celebes, with rare specimens from Vene- 

 zuela, Quito, East and West Indies, Africa and other parts of the world. — 1 Quarterly 

 Journal of Microscopical S denes'' for January, p. 69. 



[It is interesting to see this, the oldest of all entomological inquiries, again 

 revived; a similar attempt was made in 1828, when the plumules of fifty-four species 

 of male Pierides were figured, and the objects themselves examined at a meeting of 

 the Entomological Club. The idea that these plumules had ever been considered 

 " flat" is new to me. — Edward Neivman~]. 



Viscid Lines in a Spider's Web. — As I have, although very casually, alluded in 

 this paper to the large garden spiders, I may, perhaps, be allowed to mention a fact 

 connected with them which came under my notice about the same time. It is well 

 known that in all geometric spider webs the concentric lines, with the exception of 

 those in the very centre, are most beautifully dotted with a viscid substance, to aid in 

 the capture of insects. Mr. Blackwall has, I believe, computed that there are more 

 than 100,000 of these gummy drops in a web which is made in about half an hour ; it 

 has always, therefore, been a puzzle in my own mind how this part of tfie process was 

 effected, and as I had been unable to find any one who could give me a satisfactory 

 explanation, I thought I would carefully watch a spider during the operation, when, 

 with only a pocket lens, I could distinctly ?ec that the viscid lines, as first drawn from 



