232 FOREST ENTOMOLOGY. 



in summer it is green, and in winter brown. Underneath this 

 scale or " test " may be found the actual body of the insect, 

 but in the living specimens it is almost inseparable from the 

 scale, hence it is best to select dead specimens for microscopical 

 examination. 



After treatment with potash, details of structure can only be 

 seen under high powers, of which the salient features are spin- 

 nerets and rudimentary antennae. 



Genus Pseudococcus. 



The genus Pseudococcus is decidedly arboreal, and in many respects 

 resembles the mealy bug, more especially in the larval stage. 



Pseudococcus aceris (Signoret). 



In fig. 217 a typical example of this scale is represented on horn- 

 beam. To the naked eye this scale appears as a small white speck 



on the food-plant. It is found 

 on various forest trees and shrubs, 

 including sycamore, hornbeam, 

 mountain ash, elm, oak, and 

 gorse or other plants. On the 

 last-named food-plant it is some- 

 times very thickly coated on the 

 spring leaves, and at other times 

 only sparsely distributed. Though 

 never so numerically strong as to 

 be considered a pest, it has never- 

 theless an interesting life-history. 

 Fig. 217 -Pseudococcus aceris c The female insects, as seen in the 



hornbeam (natv/ral size). 



illustration, should be looked for 

 towards the end of May or beginning of June. They may be then 

 placed in a box, together with a very small portion of the host-plant 

 upon which the insect rests. The larvae hatch about the middle of 

 June, and they are mere pin-points in size, and of a light-yellow 

 colour. The antennas at this stage are composed of six joints, the 

 terminal joint being as long as three succeeding joints. They have 

 large prominent eyes, of a brown colour, with just a slight tinge of 



