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 
LampyridcB are essentially solitary in their habits. 
I will now speak of our other luminous insect, the 
Glow-fly {Pyrophorus iioctilucus). 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 Plater (known to 
me, however, only by the citation in Kirby and 
Spence’s Introd. to Ent. ii. SS3., 6th edit.) differs so 
greatly from the phsenomena 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 may be 
