A NEW MEALY BUG INFESTING WALNUT 

 APPLE AND PEAR TREES 



Pseudococcus bakeri, n. sp. 



BY E. O. ESSIG. 

 HORTICULTURAL COM .M ISSION'KR OF VENTURA COUNTY, CALIFORNLV. 



Among Other things that a systematic tree-to-tree inspection has revealed 

 in V'entura County, is a mealy bug infested wahiut, apple, and pear trees. 

 At first this insect was thought to be the long-tailed variety, Pseudococcus 

 iongispiinis (Targ. ) because of its anal appendages, which are often nearly 

 as long as the body. A great deal of excitement was caused among the 

 walnut and citrus growers at this discovery, for it was feared that the citrus 

 pest had now become spread over the entire orchard district of the county. 

 .\ ha.sty inspection of all walnut and adjoining citrus orchards followed 

 with marked results. The inspection showed that practically every walnut 

 orchard in the county was infested with this mealy bug, but never in great 

 or damaging- numbers ; and in only one case was a mealy bug found on a 

 citrus tree in an adjoining orchard and this was evidently not the species now 

 being described. The following field observations proved conclusively that 

 the new mealy bug was not P. loiii^ispiiiiis. 



1. Its anal appendages seldom exceed two-thirds the length of the 

 insect body, and is never longer than the body, while in the long- 

 tailed variety, the anal appendages are much longer than the body. 



2. The young are hatched from loose-egg masses much like those of 



P. citri, while the young of P. longispinus are born alive. 



3. In no case did we find this species on citrus trees, though it occured 

 in many orchards adjoining citrus groves. In the laboratory the 

 live individuals, as well as the eggs, were placed upon growing 

 citrus trees. In some cases the adults deposited their eggs before 

 they died, while others deserted the trees. The young, as rapidly as 

 they hatched from the eggs, crawled over the trees and the barrel, 

 in which the tree grew, and soon died. No individual was observed 

 to attack the foliage or branches at any time. On a walnut tree, 

 in the same room, other individuals multiplied readily, showing that 

 conditions were not abnormal where the experiment was being con- 

 ducted. 



Microscopical study revealed many other differences which are given in 

 the description of the species further on. 



The fact that it had such long anal appendages led to the decision that 

 it was not P. citri Risso, but was somewhat of an intermediate form between 

 Pseudococcus citri and P. longispiiiKS. Its feeding habits (It was usually 

 found feeding only upon the new bark formed around cracks or wounds on 

 the tree trunks) led to the belief that it was the elder form of P. obscurus 



