UNITED STATES DEPARTMENT OF AGRICULTURE 
BULLETIN No. 887 
Contribution from the Bureau of Entomology. 
L. O. HOWARD, Chief. 
Washington, D. C. 
September 29, 1920 
PEAR BORER. 1 
By Fred E. Brooks, Entomologist, Deciduous- Fruit Insect Investigations. 
CONTENTS. 
Page. 
Introduction 1 
History and distribution 2 
Synonymy 2 
Food plants 2 
Nature of injury 2 
The egg 4 
The larva 4 
The pupa 5 
The adult 6 
Oviposition 6 
Cannibalistic tendencies 7 
Natural enemies 7 
Methods of control 8 
INTRODUCTION. 
The common name "pear borer/ ' long ago bestowed upon the 
insect which forms the subject of this bulletin, is something of a 
misnomer, since the species attacks apple more extensively than 
pear. The name "apple crotch-borer" would be much more sug- 
gestive of the general habits of the insect. The species occurs over 
the eastern portion of the United States and in this region a few 
of the larvse usually may be found boring in the bark of almost 
any old apple tree that may be examined. So long as the attack is 
limited to only a few borers the effect on the general health of the 
tree is scarcely perceptible, but occasionally the insects concentrate 
in certain trees and there breed in numbers year after year. The 
injury which follows is cumulative, resulting in depleted vigor, and 
often in the death of a part or all of the tree. On the whole, this 
borer is more injurious than is commonly supposed. 
The following pages contain an account of this insect which is 
based very largely upon data collected by the Bureau of Entomology 
during the past five years. In gathering the data several badly 
infested apple orchards in Pennsylvania, West Virginia, and Missis- 
sippi were visited for the purpose of noting the extent of injury, con- 
ducting biological studies, and testing methods of control. 
Aegeria pyri Harris; order Lepidoptera, family Aegeriidae. 
186610°— 20 
