106 CONTENT. 



I have never seen one against the sky, hut, generally 

 speaking, their flight takes a range of only a few feet 

 or yards from the ground. The term " swarmed," 

 too, must be understood as expressing only their 

 numbers, which are often very great ; not any associ- 

 ation, like the swarming of gnats or bees, for the 

 LampyridcR are essentially solitary in their habits. 



I will now speak of our other luminous insect, the 

 Glow-fly [Pyrophorus noctilucus). From February 

 to the middle of summer this beetle is common in the 

 lowlands, and at moderate elevations. Lacordaire's 

 account of the luminosity of this Elater (known to 

 me, however, only by the citation in Kirby and 

 Spence's Introd. to Ent. ii. ooS.^ 6th edit.) differs so 

 greatly from the phaenomena presented by our 

 Jamaica specimens, that I cannot help concluding 

 that he has described an allied but very distinct 

 species, and I feel justified therefore in recording 

 what I have myself observed. The light from the 

 two oval tubercles on the dorsal surface of the thorax 

 is very visible even in broad daylight. When the 

 insect is undisturbed, these spots are generally quite 

 opake, of a dull white hue ; but, on being handled, 

 they ignite, not suddenly but gradually, the centre of 

 each tubercle first showing a point of light, which in 

 a moment spreads to the circumference, and increases 

 in intensity till it blazes with a lustre almost daz- 

 zling. The colour of the thoracic light is a rich 

 yellow-green. In a dark room, pitch-dark, this 

 insect gives so much illumination as to cast a definite 

 shadow of any object on the opposite wall, and when 

 held two inches from a book the whole line mav be 



