58 

 DESCRIPTION OF PLATE. 



FIG. 1. Flat-celled Borer (Xyleborus saxeseni, Batz.). 



FIG. 2. Wood showing flat cavities of the Flat-celled Borer in vertical 

 and horizontal section. 



FIG. 3a. Female and FIG. 3b. male of Shot Borer Beetle (Xyleborus 

 dispar, Fab.). 



FIG. 4. Wood showing circular burrows of Shot Borer Beetle in vertical 

 and horizontal section. 



FIG. 5a. Larva much enlarged (after Ormerod) of the Bark Beetle 

 (Scolytus rugulosus, Batz.). 



FIG. 5b. Bark Beetle (Scolytus rugulosus, Batz.). 



FIG. 6. Twig with portion of bark removed showing workings of the 

 Bark Beetle (Scolytus rugulosus, Batz.). The dark channels are 

 brood chambers made by the parent beetle. The smaller channels 

 are made by the larvas or young. (Fig. 5a.) 



PLUM APHIDES. 



I. LEAF-CUBLING PLUM APHIS. 

 (Aphis pruni, Keaumur.) 



Nature of Damage. The presence of this aphis is easih 

 recognised by the characteristic curling of the leaves (see 

 Fig. 1) which are often covered with sticky honey-dew. In 

 a bad attack the leaves die, the new growth is checked, and 

 the fruit is either undersized or falls off before it is ready to 

 pull. The aphides themselves live in the curled leaves. 



Plants Attacked. All varieties of plum and damson are 

 attacked, and also blackthorn, peach, apricot, and apple, 

 though to the last three little damage is done. 



Life-History. In the autumn small, shining black egg* 

 are laid on the twigs and at the base of the buds. Early in 

 spring either in March or April, according to the district 

 these eggs produce young, which grow into large purplish or 

 brownish " mother queen " aphides. The queens give rise 

 to living young, which at first are green, but when full grown 

 are often dark in colour. These aphides, which are also jof 

 the female .sex and are wingless, produce young in their tui'n, 

 and reproduction in this manner continues until late June or 

 July, when winged forms appear. The winged forms desert 

 the plums, but the plants to which they fly are not known, 

 with certainty, though Theobald has now traced them 'to 

 " Forget-me-not " both wild and cultivated. Winged forjns 

 again appear on the plums in autumn, and these give rise '10 

 males and females, the latter producing the .winter eggs. 



Natural Enemies. The plum aphis is attacked by lady- 

 birds, lacewing and syrphid flies, as well as by minute 



