127 



THE THREE PEAR TREE PSYLLAS. 



We had occasion some time since to abstract Dr. F. Loew's remarks 

 on the Psylhis which inhabit the Pear, from his Neue Beitrajj,e zur 

 Kenntuiss der PsyHiden, 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, Fnylla pyriHuga 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- ui)on the buds and 

 leaves of the pear trees. The young- larvse of PKylla pyrmiga infest the 

 leaves and the young succulent shoots, but after the second molt they 

 migrate first to the older tw^gs, 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 larvse 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 t^ags, and sometimes also the 

 underside of the leaves. 



Psylla pyrisuga is found throughout central Euroj)e, appearing almost 

 every year in large numbers, and is quite a serious j)est. Psylla pyri is 

 a comparatively rare species, appearing always in small restricted col- 

 onies, but is widely distributed. Psylla pyrieola occurs in some locali- 

 ties in large numbers, and particularly infesfs 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 withont spots, except that occasionally the jjterostigma may be some- 

 what reddish or T)rownish; 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. Pftylla 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 trout 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 apical margin. Ajtex 

 of the clavus black, with a small black siiot or shade behind it in the posterior basal 

 cell. The apes of the clavus of the hind wing is also black, or sometimes the entire 

 «lavus. 



(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 



