Nii^TH Report of the State Entomologist 



327 



tion and illustrations of the several stages, methods of preventing its 

 ravages, together with its bibliography and synonymy. 



Whether or not, eggs of the pear-tree Psylla, are, in some cases at 

 least, deposited in the autumn for hibernation, seems still an unsettled 

 question. 



Mr. Slingei*land found a hibernating brood of the winged insect, 

 in both sexes, in the month of December, hidden in crevices under 

 loosened bark of the trunks and larger branches of trees. The 

 females contained no mature eggs. During some warm days occurring 

 about the 7th of April, hibernated adults were seen in copulation and 

 a few eggs were laid. By April 18th, most of the eggs had been; 

 deposited — in crevices of the bark, in old leaf scars, and about the 



bases of terminal buds of the preceding: 

 3'ear — usually singly, but sometimes in 

 rows of eight to ten. Under a continu- 

 ance of cold weather, the eggs did not 

 hatch until more than a month thereafter, 

 or May loth to 18th, but eggs that had 

 been removed and subjected to the 

 warm temperature of the Insectarj^, gave 

 out their larvae in eleven days. The 

 larvre at once resorted to feeding grounds 

 which were usually found in the axils of 

 the pear-tree the leaf petioles or stems of the young; 

 fruit, into which they thrust their short 

 beaks and extract the sap. '' The whole life-cycle of the generatiora 

 studied, from the laying of the Q'gg to the appearance of the adult insect^ 

 was about one month " [in the Insectary]. 

 During this time, five stages — " nymph 

 stages " — of the immature insect were 

 observed, followed by the fifth molt 

 giving the winged adult. [If it be pre- 

 ferred to retain a " pupal stage " for the 

 insect, the last two of the above noted 

 may be so regarded, m w^hich there are 

 eight antenna! joints, while the preced- 

 ing show but three, four, and six or seven 

 respectively, according to Mr. Slinger- 

 land's observations.] Figures 12 and 13 

 represent the full-grown " nymph " or 

 pupa — the natural size indicated b}- the 

 accompanying hair-lines. 



Fig 



12.~Pupa of 



Psylla, do: sal view. 



^'W 



Fig. 13. 



Pupa of the pear tree Psylla ^ 

 ventral view. 



