232 B. P. Stebbing — Life-History of Ohermes abietis-piceae Steb. [No. 4, 



cone shaped green mass. When quite young there is no partitioning off 

 into distinct cells to be observed within the cone, but as the swelling under 

 this constant irritation continues, the interior gradually becomes divided 

 oil into distinct compartments, in each of which numbers of the young 

 larvae are to be found engaged in sucking up the juices of the walls of the 

 compartment. In the third week of May this partitioning is already 

 distinct, and a section of the small gall, which is by then bright green 

 externally, and pyramidal in shape, will show a number of chambers 

 situated on either side of a central axis. The young aphids are 

 still bright crimson in colour, with legs and antennae light yellow. No 

 indications of wings are apparent at this period. As the gall be- 

 comes partitioned off inside the outside presents distinct diamond-shaped 

 surfaces, each of which is the cover to a chamber below. A centre spot 

 in each of these surfaces is lighter-coloured than the rest, and may form 

 a minute projection. This would appear to represent the tip of the 

 swollen up needle. It is nevermore than a minute projection, and in this 

 differs from the European Spruce Chermes gall in which the spine or leaf 

 top projects to some distance beyond the cone surface and can be seen to be 

 the true upper portion of the needle. The false cone continues to 

 steadily increase in size throughout June, and the young larvae turns 

 to a dark purple colour. They moult several times whilst in the 

 chamber, and the white papery cast skins can be found in the cavities. 

 From 6 to 8, or at times an even greater number of larvae inhabit each 

 chamber. 



Several cones may often be found upon the same branch, and the 

 writer has seen young trees absolutely loaded with these pseudo-galls. 

 I have already described to the members of this Society* the manner 

 in which the larvae leave the false cone aud develop their wings. A 

 certain number of them on acquiring these fly off to the Silver Fir 

 where they may be found in the first half of July clinging to the new 

 year's needles. 



The subsequent history of these winged forms from the Spruce has 

 not as yet been traced. 



The Chermes on the Silver Fir. 



The presence of the spring eggs on the silver fir is easily discernible, 

 since they are invariably covered or partially covered with a white 

 cottony material. At times this substance is so abundant as to clothe 

 the bark of young trees more or less thickly from top to bottom, either 

 entirely encircling the stem or occupying one or two sides only. At 

 other times it is to be found only upon the upper portion of the stem of 



* Vide No. 2, p. 57 of this Volume. 



