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Dr. LeConte next read a paper on the so-called " Lightning Bugs " (Lampyridce). 



Mr. Austin remarked that when a fire-fly is at rest there is a faint ray of light visible, 

 proceeding from the edge of the segments of the abdomen ; when the insect is emitting 

 the flashes of light it moves these segments, and so reveals more of the light. 



Mr. Martin stated that he had observed a fire-fly in a spider's web, and that it emitted 

 very rapid flashes of light at first, but that they gradually diminished in brilliance till at 

 length they died out. 



On motion, the meeting then adjourned till 8 o'clock, p.m. 



Tuesday Evening Session. 



At 8 o'clock, the Entomological Club met at the Hotel Yendome, Dr. J. G. Morris 

 in the chair. 



Mr. H. F. Bassett, of Waterbury, Conn., gave an account of the "Structure and 

 Development of certain Hymenopterous Galls." He exhibited specimens of galls produced 

 on plants and trees, and spoke of the alternation of two forms belonging to one species. 

 The seminator deposits its eggs in the young acorn, and from the sting or puncture the 

 gall grows, having the appearance of another acorn. This falls to the ground in September, 

 and remains twenty-one months, at the end of which time the gall-flies are produced, which 

 are all females. These females lay their eggs in the buds of the trees in the spring, and 

 from these galls are formed, out of which are developed flies of both sexes. All galls may 

 be divided into two classes : — First, those formed in autumn, which do not develop till 

 the next or a succeeding year, the imagoes or perfect insects hatched from them being 

 always females ; and secondly, those formed in the spring, the progeny of which are of 

 both sexes. He considered that the woolly substance that covers these galls is an excessive 

 development of the pubescence of the leaf, and thought that the growth of the galls is 

 produced by the^action of the poison that is infused by the parent insect when making the 

 sting or puncture, because he often could find in a gall no trace of any larva. 



Prof. Riley expressed his opinion that galls are formed both by the poison injected 

 with the egg, and by the irritant action of the larva. He spoke also of the sweet exuda- 

 tion on galls, and remarked that honey-dew is in some cases the natural exudation of the 

 plant, independent of the action of insects upon it. 



Prof. C. H. Fernald, of Orono, Me., exhibited three volumes recently published by 

 Lord Walsingham, on "North American Micro-Lepidoptera, Tortricidse," illustrated with 

 coloured plates, and forming part of the British Museum Catalogues for 1879; also, by the 

 same author, a volume on the "New and little-known Species of North American Tineidae," 

 and another on "The Pterophoridse of California and Oregon." He then proceeded to read 

 a paper on the Classification of Tortricidce, illustrating his remarks by some wings prepared 

 for the microscope. These slides, which beautifully exhibited the venation of the wings, 

 were mounted with glycerine boiled gently over the lamp; the wings were bleached by 

 Dimmock's process. 



Dr. H. A. Hagen, of the Museum of Comparative Zoology, Cambridge, Mass., read 

 a paper on the importation of the Hessian fly. The generally accepted theory, from which 

 the insect derives its common name, is that the insect was brought from Europe to 

 America, about a century ago, in the straw used for bedding by the Hessian troops 

 employed by the British Government in the war of the Revolution. This theory Dr. 

 Hagen rejects, and in a sketch of the history of the movement of these troops, he showed 

 that the lapse of time during their transportation was considerably greater than that of 

 the term of the normal development of the fly from the egg. He stated that there was 

 some evidence of the existence of the fly in America before the arrival of the Hessian 

 troops, and that it was unknown in Central Europe till recently ; there was, however, 

 some evidence that it may have appeared in certain places on the Mediterranean coast at 

 an earlier period. He even thought it possible that the fly might have been imported 

 from America into the Mediterranean region of Europe by American trading vessels. 

 His conclusions, as stated in a long and very interesting paper, in which he quoted many 

 German and British official records, may be summed up briefly as follows : 1. It is impos- 



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