UNITED STATES DEPARTMENT OF AGRICULTURE 
Contribution from the Bureau of Entomology 
L. O. HOWARD, Chief 
Washington, D. C. PROFESSIONAL PAPER December 11, 1916 
THE PEAR LEAF-WORM. 
By R. L. Nouearet, Entomological Assistant, and W. M. Davipson and E. J. New- 
COMER, Scientific Assistants, Deciduous Fruit Insect Investigations. 
CONTENTS. 
Page Page 
EM ERO GUCTION irs eA OSM Nite niy Ne iis Pr RBIOLOS We raat cms mene s ce hue eto aOmimp io ae 9 
History anddistribution’ - 9.20824 82522222. Li Na tural: controle sane hasan a pede e 17 
Possibleronigiwy 4h pele ee oul ee 2ule Remedialimeasuresaad 222 43 bassececeis ace 18 
Character and extent of injury............... Sal PSUMM Ages Meee ence cree eta ee 22 
Descriptionand habits: ose 22 ee coe ee 4+|» Bibliography. +. 4. 2eeees AER es eee ved 23 
INTRODUCTION. 
The pear leaf-worm, more scientifically termed the pear sawfly 
(Gymnonychus californicus Marlatt), is an hymenopterous insect 
belonging to the family Nematidz and to the subfamily Nematine. 
For several years it has been noted as a pest on pear trees on the 
Pacific coast. The observations and experiments recorded herein 
were made in California by Messrs. R. L. Nougaret and W. M. David- 
son, during the years 1911 to 1914, inclusive, and in the State of 
Washington by Mr. E. J. Newcomer, during the seasons 1914 and 
1915. 
The injury is caused almost entirely by the feeding of the green 
wormlike larva and is confined to the foliage, resulting in partial 
defoliation. 
In the localities in which it occurs the insect is quite abundant. 
Occasionally it becomes a pest of serious consequence, and under favor- 
able conditions it might cause widespread damage. 
HISTORY AND DISTRIBUTION. 
The pear leaf-worm was described from 1 female collected at 
Brockport, N. Y., and 10 females taken near Sacramento, Cal., by 
NotEe.—This bulletin is of interest to pear growers Eee but especially to those of the Pacific coast. 
57170°—Bull, 488—16——1 
