1916] CoccidcB and Aphididce on Pines 421 



needles were pricked in the region of the resin ducts with 

 Minutien-Nadeln, which are very small needles, commonly- 

 used for pinning tiny insects. Effects of the punctures were 

 noted as follows: Out of 20 pricks, four showed an exudation 

 of gum. After two weeks two of these gave evidence of 

 infiltration. At the end of the second week, the spots were 

 small. They continued to grow larger. 



IV. Conclusions. 



We can say, therefore, that the damage to the needles of 

 pine trees by aphid feeding is : 



(1) From the honey dew fungus, which makes the trees 

 unsightly and interferes with the process of photo synthesis, 

 or food manufacture, in the needles by shutting off part of the 

 light; 



(2) By discolored areas from which food has been taken 

 and which have been whitened by admission of air to the cells ; 



(3) By the making of conspicuous, infiltrated spots and 

 causing gum exudation; 



(4) Inconspicuous damage by the great number of piercings 

 and suckings. This, though usually invisible, is probably more 

 important than the first three taken together. 



The damage to pines by the coccids studied is due to sucking 

 and the enzyme action of the saliva injected to assist in this 

 process. The damage consists of the destruction of chlorophyll- 

 bearing cells with a subsequent whitening of the needles. This 

 is followed by the death of the needles in some cases, or, occasion- 

 ally, by the production of infiltrated spots that, while con- 

 spicuous, are not of great importance. 



