127 
THE THREE PEAR TREE PSYLLAS. 
We had occasion some time since to abstract Dr. F. Loew’s remarks 
on the Psyllas which inhabit the Pear, from his Neue Beitrage zur 
Kenntniss der Psylliden, and as the subject is of interest in this coun- 
try we reproduce it here. 
The Pear (Pyrus communis L.) is known to be the food plant of three 
species of Psylla, viz, Psylla pyrisuga Foerst., P. pyri L., and P. pyricola 
Foerst., the last of which also occurs occasionally on the Apple (Pyrus 
mali). The imagoes of these species appear from June to August, de- 
pending on the climate, and when first matured are light in color, but 
gradually assume a darker coloration as the season advances. They 
hibernate over winter in the crevices of bark and other protected situ- 
ations, and deposit eggs in the fall and spring upon the buds and 
leaves of the pear trees. The young larve of Psylla pyrisuga infest the 
leaves and the young succulent shoots, but after the second molt they 
migrate first to the older twigs, but still of the same year’s growth, and 
later go gradually to the older and more woody parts of the previous 
year’s growth and cover it in larger or smaller closely-packed clusters. 
The larve of Psylla pyri and P. pyricola, on the contrary, always ap- 
pear on the stunted or fruit-bearing twigs, where they inhabit the buds 
and the angles between the petioles and twigs, and sometimes also the 
underside of the leaves. 
Psylla pyrisuga is found throughout central Europe, appearing almost 
every year in large numbers, and is quite a serious pest. Psylla pyri is 
a comparatively rare species, appearing always in small restricted col- 
onies, but is widely distributed. Psylla pyricola occurs in some locali- 
ties in large numbers, and particularly infests dwarf Pears and the 
varieties which are trained on trellises, and often occasions consider- 
able damage. The following characters will serve to separate the three 
Species mentioned: 
(1) The entire length to the tip of the closed wings of the male at least 3.7 milli- 
metres; of the female at least 4 millimetres. Front and hind wings colorless, trans- 
parent, and without spots, except that occasionally the pterostigma may be some- 
what reddish or brownish; the forceps of the male viewed from the side is straight 
and of uniform width to near the tip, where it tapers suddenly to a point, and is 
about three-fourths the length of and as broad or a little broader than the genital 
plate. Psylla pyrisuga Foerst. 
(2) Entire length to the tip of the closed wings in the male not exceeding 3.5 milli- 
metres; in the female 3.7 millimetres. General color of the front wings either pale 
wine yellow or hyaline and marked about the middle of the cells with yellowish, 
brownish, or blackish shades, particularly in the region of the apicalmargin. Apex 
-of the clavus black, with a small black spot or shade behind it in the posterior basal 
cell. The apex of the clavus of the hind wing is also black, or sometimes the entire 
clavus. 
(a) Frontal cones or protuberances of pale specimens yellowish or greenish white 
‘or with a brownish ring at the apex in front. In dark-colored specimens the 
frontal cones are reddish brown or dark brown, with a large yellow or reddish 
