132 THE BOOK OF GARDENING. 



insecticides. The foliage should first be sprayed and then 

 dusted with tobacco-powder. 



Leaf-cutting Bee. — -The common Leaf-cutting Bee {Megachile 

 tircumcincta) is responsible for the removal of the semicircular 

 pieces of foliage from Rose-trees, more especially from Marechal 

 Niel. The insect belongs to the Solitary Bees; and to the 

 group Andrenidce, which are chiefly characterised by their 

 short tongues. The pieces' of foliage so deftly removed by the 

 female are required for the furnishing of her nest. She is smaller 

 than the Honey Bee, and has a black back and yellowish- 

 downy head. Though it is annoying to have foliage removed 

 in the manner very familiar to Rose-growers, yet one cannot 

 help admiring the little creature as, poising herself above a 

 Rose-tree for a second or two, she rapidly snips away a piece 

 exactly suited to her requirements — -no mistake is made as 

 to measurements — and away she flies with the piece held by 

 means of her jaws and her legs. Having placed it in posi- 

 tion, she sallies forth again until her nest is complete. Unlike 

 the Social Bees, she has no workers to help in the ela- 

 boration of the house — she is architect and forager, labourer 

 and queen-mother. The food is next deposited ; it consists of 

 pollen and nectar, which are carefully mixed, and on this is 

 deposited a single egg. Another cell is made, and the food' 

 preparation and egg deposition are repeated until the requisite 

 number of cells have been completed and sealed. The eggs 

 first laid produce females, and those last males. The latter are, 

 of course, the first to emerge, feed up, leave their snug retreat, 

 and having performed the part which Nature has allotted them, 

 die. The females produced hibernate to begin another season 

 the cycle anew. Those who object to the foliage being dis- 

 figured must either catch the industrious little workers in a net, 

 or else insert some plant which is objectionable in the vicinity 

 of the Roses — Pyrethrum is as good as anything. 



Scale Insects. — A whitish scale insect (Diaspis rosce) is said to 

 infest Rose-stems very occasionally, but it is so rare as to be 

 hardly worth consideration. 



Fungoid Diseases. — These are fairly numerous, but there are 

 two or three which stand out from the rest on account of their 

 markedly unsightly character — Mildew (Spkcerotheca pannosd), 

 Actinonema rosce, and Orange Rust (Phragmidium subcorticium). 

 The first is characterised by a greyish mildew, which covers 

 leaves, stems, and frequently the fruits. Indeed, it is by means 



