THE PACIFIC COAST SPECIES OF XYLOCOCCUS. 

 (SCALE INSECTS). 



Laura Florenxe. 



In 1882, at the December meeting of the Societe Entomol- 

 ogique de France, M. Victor Signoret (12) read a note from Dr. 

 Franz Low, calling attention to a recent publication by the 

 Societe Zoologique et Botanique de Vienne, of the description of 

 a new Coccid for which he had created a new Genus Xylococcus. 



The paper was published in 1882, under the title of " Eine 

 neiie Cocciden Art (Xylococcus filif ems)'' (10). The insect was 

 first discovered and sent to Dr. Low in 1878, and he had it 

 under observation from that time until the publication of his 

 paper. He described in detail the first larval stage and the 

 adult female, giving only a brief general description of an indefi- 

 nite number of intervening stages. The remainder of the paper 

 was occupied with notes on the life history, the position of the 

 insects on the tree, and their method of penetrating into the 

 lower layers of the bark. 



There is no further reference to Xylococcus to be found until 

 1890, when in a paper entitled ''How do Coccids Produce Cavities 

 in Plants?'' the author, Mr. W. M. Maskell (11), cited it as an 

 example of a cavity-producing Coccid. 



In 1898 a paper was published by H. G. Hubbard and Th. 

 Pergande (6) on a new Coccid found on birch trees. Thus a 

 second species of Xylococcus was recorded, the first to be found 

 in America. This, having been found on birch trees in Lake 

 Superior region, was named Xylococcus hetulce by Mr. Pergande. 

 The paper was in two parts, the first by Mr. Hubbard was 

 biological, the second by Mr. Pergande structural. In this 

 paper were well pointed out the extremely interesting peculiar- 

 ities, both structural and physiological, of these curious Coccids. 



Both the above-mentioned species were listed by Professor 

 T. D. A. Cockerell (1) in his " Tables for the Determination of the 

 Genera of Coccidce." He divided the sub-family MargarodincE 

 into two tribes, Margarodini and Xylococcini. In the latter he 

 placed Xylococcus and two allied Genera Coleostoma and 

 Callipappus. 



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