PEAR PESTS 



1653 



upon the eggs and larvae of the pear 



psylla. 



E. O. EssiG 



Peae Slug. See GJierry Pests, 

 Pebiodical Cicada. See Apple Pests. 

 Pistol Case Bearee. See Apple Pesis. 

 Plum Cubculio. See Plum Pests, 

 Red Scale. See Grape Pests. 

 Saw Jose Scale. See Apple Pests. 

 Scurfy Scale. See Apple Pests. 



Sesian 



Sesia pyri 

 Throughout all of the autumn months 

 a borer may be found working in 

 the bark of pear and sometimes in 

 that of apple trees. Its presence is indi- 

 cated by castings, resembling fine saw- 

 dust, thrown out upon the bark of the 

 tree. The larva is whitish to pink and 

 does most of its feeding under and in the 

 bark, injuring the sapwood but little. The 

 adult is a clear-winged moth, having a 

 wing expanse of about three-fourths of 

 an inch and a pair of yellow bars cross- 

 ing the abdomen transversely; a fan- 

 shaped tuft of hairs at the end of the 

 abdomen is of the same color. It appears 

 in summer and deposits the eggs for the 

 worms which appear in early fall. It is 

 known as the apple or pear sesian. The 

 most satisfactory method of destroying 

 the worms is to dig them out and kill 

 them. Whitewashing or painting prop- 

 erly the trunks of the trees in early sum- 

 mer is probably of some value in discour- 

 aging egg-laying. 



H. A. GOSSARD, 

 Wooster, Ohio. 

 Shot-Hole Bokee. See Cherry Pests. 

 Spring Canker Worm. See Apple Pests. 

 Tarnished Plant Bug, See Straw- 

 'berry Pests. 

 Tent Caterpillar. See Apple Pests. 



Pear Tlirips 



Physothrips (Euthrips) pyri Daniel 



S. W. Foster 



Distribution 



The pear thrips is at the present time 



very destructive in the San Francisco 



bay region and the larger part of the 



lower Sacramento valley of California. 



More recently it has been found in de- 



structive numbers throughout New York 

 state and Northwestern Pennsylvania. 



Economic Importance 



It is at the present time the most im- 

 portant insect pest with which the grow- 

 ers of deciduous fruits in the sections 

 mentioned have to contend. On account 

 of the minute size of the insect, the rap- 

 idity of its spread over large areas, and 

 the suddenness of attack in great num- 

 bers — completely blasting in a few days 

 all prospects for a crop — the control of 

 this pest is a matter of considerable 

 difficulty. As the insect is each year 

 extending its range of food plants, its 

 capabilities for dissemination are cor- 

 respondingly increased. There is no rea- 

 son to believe that the insect will dis- 

 appear, it should be regarded as a per- 

 manent and serious pest. Conservative 

 estimates place the damage caused by the 

 pear thrips in California during the years 

 from 1904 to 1912 at least $6,000,000. It 

 is safe to say that the thrips in the ab- 

 sence of treatment would cause an aver- 

 age yearly loss to the state of over 

 $1,000,000. 



Character of Injury 



Injury to the various fruit trees by 

 this species is caused by the feeding of 

 the adults on the developing buds and 

 yearly blossoms; by the deposition of 

 eggs into the fruit stems, leaf stems and 

 newly formed fruit, and by the feeding 

 of the larvae in the blossoms and on the 

 young fruits and foliage. On pears the 

 greater injury is produced by the adults, 

 which often prevent the trees from 

 blooming, while on prunes and cherries 

 the larvae frequently prevent a crop of 

 fruit from setting after the trees have 

 come into full bloom. Also, the deposi- 

 tion of eggs into the fruit stems of 

 prunes and cherries so weakens the 

 stems that much of the young fruit falls. 

 By rasping the tender surfaces in the 

 developing fruit buds and the young 

 fruits with their hardened mouthparts, 

 the thrips rupture the skin, causing an 

 exudation of sap which is often followed 

 by more or less fermentation, especially 

 before blooming. The feeding by larvae 



