March, 1917] WiLLIAMS : NORTH AMERICAN LaMPYRID.E. 15 



over into the third instar. When ready for the first moult they are 

 about 3 mm. long. I kept these insects in a jar of moist earth and 

 fed them flies which were cut up so that they could be devoured more 

 easily. Several larvje would gather about a fly and bore their way 

 into it till their heads and a portion of the prothorax were hidden 

 from view. They remained thus for some time, so that when a day 

 later I examined the larvae, I found them all dead from suffocation. 

 Like Photiiris, they pass the greater part of two years as larvae, and 

 like the former, the same brood is sometimes characterized by the un- 

 equal growth of some of its individuals, so that there are larvae which 

 probably require less and others more than two seasons to produce 

 adults. No first-year larvae were taken in the field. Newport, in 

 rearing Lampyris noctiluca, noticed different rates of growth among 

 the larvae under apparently the same conditions. He adds that they 

 may not all mature the same year, for as much as one year and nine 

 months may elapse before full growth is attained. 



The full-grown larva is about 13 mm. long, exclusive of the head, 

 and with the head extruded, 14.5 mm. The head is depressed, sub- 

 cylindrical, somewhat longer than wide, and about half as wide as the 

 prothorax. The antennae are three-jointed, with two terminal sense- 

 organs. The body is slendjer and depressed and a little wider at the 

 middle. The tergites are heavily chitinized and coarsely punctate 

 and rugose, while on each side of the dorsal median line is a rather 

 indistinct carina, most evident on the thorax and tending to disappear 

 posteriorly. The legs are slender and the prolegs very much divided 

 into dichotomously branching filaments. The dorsum is shining black, 

 the ventral sclerites are smoky brown and the membrane is dirty 

 whitish, with the exception of the venter of the thorax as well as the 

 sides above the lateral line, where there is often a decided suffusion of 

 pinkish. The legs have the chitinous portion testaceous. The head is 

 black and the mandibles reddish brown. The body has rather sparse 

 yellowish-brown hair. The adipose tissue gives the anterior part of 

 the body a pinkish tinge. The larvae of Ph. pyralis (Rep. N. J. State 

 Mus., p. 298, 1909) and Ph. modestus (Kellogg's American Insects, 

 p. 269) much resemble that of consanguineus. 



It seems evident that a larva of the form of Photiniis is not so 

 well fitted to lead an active life above ground as that of Photiiris. 

 As a matter of fact, it is much more subterranean in its habits and 



