808 



FAMILY XL. LAMPYRIDiE. 



The fireflies are medium or small-sized, elongate or oblong, , 

 beetles of soft structured mostly plain black or brownish in color 

 and often having the thorax bordered with red or yellow and ex- 

 panding into a thin projecting margin which, in many species, 

 covers the head. They have the maxillae exposed at the base and 

 bearing two ciliate lobes, the inner of which is sometimes obsolete; 

 antenme serrate, usually 11-jointed and inserted on the front ; elytra 

 thin, flexible, sometimes short and never strongly embracing the 

 sides of abdomen, the latter with seven or eight free ventral seg- 

 ments; front coxal cavities large, transverse, the coxa? conical, with 

 large trochantins ; middle coxa? oblique, usually contiguous ; hind 

 coxa? transverse and prominent; legs long, slender, often com- 

 pressed; tarsi 5- jointed, not lobed beneath, the fourth joint more or 

 less bilobed. 



The name ' 'Lampyrida?" is derived from a Greek word meaning 

 ''to shine," and refers to the property above mentioned which many 

 of the larger forms possess, viz., that of emitting a phosphorescent 

 or luminous glow. This light-giving apparatus is located on the 

 under side of one or more segments of the abdomen and is com- 

 posed of a specialized portion of fatty tissue, situated directly under 

 the soft chitinous cover and thickly supplied with nerves and fine 

 tracheal branches. ' £ The cells of this luminous organ secrete, under 

 the control of the nervous system, a substance which is burnt dur- 

 ing the appearance of the light ; this combustion takes place by 

 means of the oxygen of the air conveyed to the cells of the luminous 

 body by the trachea?, which branch profusely in it and break up 

 into capillaries." The burning takes place without producing 

 sensible heat, is controlled by the will of the insect and is intermit- 

 tent, being exhibited by flashes. It is a vital phenomenon and 

 ceases after death, but the luminous segments can be recognized in 

 dried specimens by their yellow hue. 



That the light-giving power is of especial importance to the true 

 fireflies, which all belong to the subfamily I.ampyrina?, is shown by 

 the fact that they usually have the eyes largely developed, and that 

 they are nocturnal insects, being sluggish by day, when they rest 

 upon the ground, the trunks of tree^ or the foliage of herbs or 

 grasses. The property of emitting light is possessed both by the 

 perfect insect and the larva?, the latter, as well as the wingless 

 females of certain species, being known as "glow-worms." Those 

 belonging to the other subfamilies are diurnal in habit and are 

 usually found upon flowers or running actively about over leaves in 



