260 STATE HORTICULTURAL SOCIETY. 



had become of a dark crimson hue. In some cases the nymphs in this 

 stage were yery distinctly marked, differing from the full-grown nymphs 

 only in having fewer and larger black spots on the thorax. The duration 

 of this stage was about four days. 



At the fourth moult, the markings which had been faintly visible since 

 the second moult now came out very distinct. This proved to be the last 

 nymph stage. The general appearance of the full-grown nymph i& 

 described at Fig. 2. The black markings are represented in figures 1 

 and 2. 



After feeding five or six days, the nymphs moult for the last time; at 

 this moult the adult insect crawls from the nymph's skin. European 

 observers -have recorded but four moults for the nymphs of several species 

 of Psyllidae. The observations at the insectary were made upon several 

 individuals isolated in small cages which were under daily observation 

 from the emergence of the nymph from the egg to the appearance of the 

 adult insect. 



In each stage the nymphs secreted globules of honey-dew several times 

 larger than themselves; sometimes the globule completely enveloped a 

 nymph. After each moult the nymphs usually sought a new feeding place, 

 leaving the old skin attached to the drop of honey-dew. The old moulted 

 skins, of the last moult especially, often retained their form almost 

 perfectly. So life-like did some of them appear, with the legs and antennae 

 naturally placed, that it often required close examination with a lens to 

 determine whether the object was a live nymph or only the cast-off" 

 garment of one. 



The whole life cycle of the generation studied, from the laying of the 

 egg to the appearance of the adult insect, was about one month. The 

 adults upon emerging are of a delicate greenish color; the blackish mark- 

 ings soon appear, however, and in two or three days the green changes to 

 the normal reddish brown color. Although the adults are so distinct sex- 

 ually, there seems to be nothing abo&t the full-grown nymphs which would 

 indicate the sex of the adult soon to emerge from the nymph's skin. 



The adults begin feeding at once after emerging, but do not increase 

 visibly in size. They appear to secrete no honey-dew, but void consider- 

 able quantities of a whitish excrement. Adults of the summer broods- 

 lived for several days in cages in the insectary; how long they live under 

 natural conditions has not been ascertained, probably less than a month. 

 The adults which hibernate, however, remain alive for at least six months. 



About a week after the summer broods of 

 adults emerge, copulation takes place and the 

 deposition of eggs soon begins. The winter 

 brood, as has been said, do not, however, 

 copulate and oviposit until spring. Several 

 of the adults were observed with a lens while 

 in copulation. The operation was of par- 

 ticular interest; for a glance at figures 5 and Fig. .=>.— Abdomen and genital organs of 

 6£ , 1 11 ■ 111 -11 the male, eirie view; a, anas; f, for- 



Or the sexual characters and abdomen will cepe; l, lower genital plate; p, penle; 



show that the male organs (Fig. 5, a,/, /, p, a. npper genital plate. 

 M.) are so peculiarly situated as to seemingly render the grasping of the 

 female organ ( Fig. 6, a, e, I, u. ) no easy matter. It was found, however, 

 that the caudal segments of the abdomen of the male were very flexible 

 and enabled the trough or lower male genital plate (Fig. 5, /) to be curved 



