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Fig. 1. 



ENTOMOLOGICAL RECORD. 



Bv TowNEND Glover, Entomologist. 



Luminous Beetles. — As it does not appear to be generally known 

 that aluminous beetle closely resembling the "cmcm?/o" or fire-fly of the 

 West Indies is found abundantly within the limits of the United States, 

 and although the fact may not be of any value to the agriculturist, it 

 must yet be interesting to entomologists in general. We, therefore, 

 make extracts from a letter from a valued correspondent, 

 Mr. N. B. Moore, Manatee, Florida, who at the same time 

 forwarded with his letter specimens of an insect, which proves 

 to be the Pyrophorus physoderus, (Fig. 1,) a species of 

 snapping-beetle, and closely resembling the Pyrophorus 

 noetilucns, (Fig. 2,) or far-famed fire-fly of the West Indies, 

 with exception of size, as will be seen by the wood-cuts. 



Mr. Moore writes that " these insects are very plentiful 

 on the ' pine barrens ' and among saw-palraettoes, having 

 captured as many as nineteen on the 28th of August. 

 The common ' lightning-bug,' or fire-fly, [Photinus pyralis,) 

 is also abundant, but appears an hour earlier in the eve- 

 ning, and, no doubt, has often been mistaken for this 

 insect. In its manner of flight the Pyrophorus seldom 

 rises more than three feet above the earth, so as to 

 pass close over the tops of the vegetation. Their flight is also 

 much slower and more meandering. The light is emitted 

 from the reservoirs of the thorax at the base of the spines 

 and through them. When on the wing it is generally, if uot always, con- 

 tinuous, and equal in amount, as seen from above or below. I do not 

 think it is remittent, and there is no flash, and in amount there is less 

 than the Photinus pyralis emits at the time of its flash; there is no per- 

 ceptible difference in the color of the light of the two species except 

 that which rises from degree of intensity. Its utmost luminosity is 

 attained when running on the ground. When placed upon a quilt or pil- 

 low an almost dazzling effulgence emanates from the thoracic reservoirs, 

 seemingly from the disks or perhaps globes, one at the base of each 

 spine. If caught and held between the thumb and finger gently, the 

 same effulgence is emitted. If the insect stops running or takes wing 

 the light emitted is much less, though a fixed increment. 



" Experiments in a dark room, with eighteen of the Pyrophorus and 

 one of the common Photinus on a table, enabled me to compare the light 

 of one of the former with that of the latter at their maximum brilliancy, 

 and I find them about equal; though, as one is a flash and the other a 

 continuous light, I think the latter is really superior. I have not found 

 the one, when in its native habitat, intruding upon the possessions of 

 the other, but they keep apart. When examining them with a glass, I 

 discovered, while observing one that lay upon its back, other sources 

 of illumination ; luminous dots, in pairs, were first detected along the 

 lateral margins of the abdomen, and transversely opposite; the ante- 

 rior pair rather faint, indeed not discovered till after the next succeed- 

 ing pair were seen; the next bright; the third pair I would rate be- 

 tween them in luster ; a fourth pair a little fainter; these, united by 

 a line of light extending across the abdomen, at the junction of the seg- 

 ments. I could discover no trace of concurrent or sympathetic action 

 between the light emanating from the thorax and that from other parte 



