19 



that the male during its successive transformations retained both its 

 antennae and legs, but while happening one day to explore, in search 

 of the mature male, a jar containing two sections of branches of birch, 

 I discovered two living male larvae, one of them in the act of casting- 

 its skin, and found to my surprise, after the insect bad been extracted, 

 that the cast skin showed all the characters of a young female in the 

 second stage, in which there are neither an tenure nor legs; whereas in 

 the form which had emerged from it these organs were highly devel- 

 oped. The rostrum, however, had been lost. This organ in the female 

 is present in all stages except the last. 



After examining and comparing the abundant material at hand of 

 both sexes, I have arrived at the conclusion that this small and apodous 

 form of the male is the third stage, differing from the second stage of 

 the female in its somewhat larger size, the darker brown color of the 

 posterior half of the body, and in minor characters. 



I append herewith a description of the different stages of the two 

 sexes, including the egg. 



Xylococcas betulce n. sp. 



Egg. — Length 0.6 mm by 0.3 mm in diameter; regularly oval, highly 

 polished, and of a pale yellow color. 



First larva, after hatching. — Length about 0.5 mm by 0.3 mm across the 

 broadest part of the abdomen. Color orange-red, the eyes purplish. 

 Shape cimiciform, the abdomen very broad and semicircular behind. 

 The thoracic and three or four anterior segments of the abdomen are 

 highly developed, whereas the remaining segments of the abdomen 

 form apparently a single piece. The anal or excretory tube is large, 

 chitinous, and partly projecting. Antennae six-jointed, very short and 

 rather stout; joints one and six are somewhat the longest and subequal 

 in length; the intermediate joints are shorter and also subequal in 

 length, or the second slightly longer. The first is stoutest; all the 

 others diminish gradually in diameter; the last is bluntly rounded at 

 the apex. At the base of joint five externally will be noticed one long 

 and stout, blunt and curved, spine. There are two similar spines at 

 the base of the last joint, with four or more slender capitate hairs and 

 one or two small spines at its apex, two or three of these hairs being 

 at least as long as the antenna?, Eyes large and placed close to the 

 antennae. Legs long and stout; the tarsi longer than the tibiae; digi- 

 tizes capitate, those of the claw somewhat the longest, stoutest, and 

 curved upwards. Rostrum large, the sucking bristles extremely long. 

 Each abdominal segment is provided with a large and projecting spir- 

 acle and a pair of backward-directed spines each side, which grow 

 gradually longer toward the end of the body; in addition, a number of 

 stout spines surround the anal tube. There is also a rather long bristle 

 each side of the seventh segment. (See fig. 2, a.) 



When the larvae are about to cast their first skin they measure nearly- 



