60 E. P. Stebbing — Alar appendages of Ohermes abietis-picese. [^°- 2, 



Total length of insect with wings is 468 mm. The wings project 

 beyond the posterior end of the body about li times the total length of 

 the aphid. The Ghermes is short, thickish, almost squarish in build and 

 appears somewhat natter after its final moult. The head is small > 

 antennsB six- jointed, the first joint very small, second aud third small, 

 fourth longest ; prothorax broad and much channelled ; the rest of 

 thorax also broad the metathorax being sessile upon the abdomen. Fig. e, 

 shows a dorsal and side view of the winged form. 



Within one and a half hours of shedding the last skin, patches of 

 white setae begin to appear upon the aphid, and the meso- and meta- 

 thorax turn from orange to shining black. These hirsute white patches 

 appear on the head, upon each division of the thorax, and two little tufts, 

 set side by side on each segment, run medianly down the dorsal surface 

 of the abdomen. On the prothorax these white set© are in a transverse 

 ridge ; on the meso- and meta-thorax they are in two large patches as on 

 the abdomen. The wings become a paler green, the costal and median 

 nervures being strongly marked and orange in colour, the transverse 

 intersecting ones being silvery. 



The insect by now, i.e., within three hours of its last moult, has lost 

 all its brilliant colouring and has become dull and inconspicuous. It 

 only differs from the winged form to be found at this period on the 

 needles of the silver fir in having a green tinge in the wings, those of 

 the silver fir fly being colourless but irridescent in certain lights. 



