Where these four chafers are prevalent there is no cure but hand-picking. The beetles must be collected off the bushes; and the grubs carefully picked out of the roots, if we have reason to think they are present from the rose appearing unhealthy. Or they may be tempted out of the soil by placing grass turves upside down close to the plants, when they can be picked out and killed with a little boiling water.
The Rose Leaf-cutting Bee spoils the foliage by cutting semi-circular pieces out of the leaves to line its nest. A few years ago I found that a fine young plant of Tea Rambler was so relished by this bee that hardly a leaf was left intact. There is no cure but to watch the bee going into her nest and there to destroy it after dusk.
Of all pests that the rose-grower has to fight against
Caterpillars and Maggots
are the very worst. For there is no real remedy against their endless and varied depredations save hand-picking; or as some one has tersely put it, "just a little gentle washing with non-caustic substances, and just a lot of finger-and-thumb work." This is tedious, and often disgusting; but it is the only way.
These loathsome pests are the larvæ of certain flies and many kinds of moths.
Sawflies, the little black and shiny flies which infest the roses in May and June, are a terrible pest, as the eggs they lay on the leaves turn quickly into small, green larvæ. There are several kinds of sawflies, and their destructive methods vary. The Leaf-rolling Sawfly, whose larvæ roll the rose-leaves like paper spills, has become a serious pest among garden roses of late years, and if these rolls are carefully unfolded the little green maggot will be found in one of them. It must be caught with care, as it is very lively, and if allowed to fall to the ground will remain there, and produce a fresh brood in the next year.
The Rose Slugworm is much more common, and most destructive, eating the upper surface of the leaves and leaving the lower to shrivel up. It has two broods in the year.
The Rose Emphytus is another of the sawflies, and one of the worst. Its larva eats the whole leaf away, beginning at the mid rib, and also works its way into a cell in the branches till the next spring, thus killing the tender growths above. This is the green caterpillar which we find coiled up on the under-side of the rose-leaves, or in early morning and late evening curled round the base of a rose-bud, working its way through the calyx into the heart of the flower. It is far easier to catch, as it is somewhat sluggish in movement, clean and hard in substance—and therefore less disgusting to touch than others that squash in one's fingers. The best remedies for these pests are: first, prevention, by spraying with hellebore wash, which I have found most useful. Second, by careful hand-picking when the larvæ appear. And third, by removing the surface soil in which the cocoons are buried, and all dead wood, during the winter.