Rosemary
(Rosmarinus officinalis). A well-known, hardy, evergreen shrub, grown in small quantities in almost every garden. The foliage is used for making what is called Rosemary tea, a decoction sometimes employed, amongst other purposes, for relieving headache. Rosemary may be propagated by seeds, by cuttings, and by layers. Seeds may be sown upon a warm, sunny border. Cuttings, taken in summer, about 6in. long, and dibbled in a shady border, under a hand glass, will root, and be ready for transplanting into permanent quarters the following autumn. Layering may readily be accomplished, in summer, by bringing some of the lower branches down, and pegging them beneath a little sandy soil. Rosemary succeeds best on a light, rather dry, soil and in a sheltered situation, such as the base of a low wall with a south aspect. There are three varieties, namely, the Common or Green-leaved, the Silver-striped, and the Gold-striped. The two last-named are not quite so hardy as the common variety.
ROSE SAWFLIES. Among the most hurtful of insect parasites of Rose-bushes are the Sawflies (Ten-thredinidae); a considerable number feed as larvae either in Rose-twigs or upon the leaflets. Some of these, so far as is known, are confined to Boses for their food, while others feed also on a variety of other plants. The fullest information on the British species is to be found in Mr. Cameron's "Monograph of British Phytophagous Hymenoptera." Not only are the descriptions in the work clear and definite, but the figures of larvae and insects are a most efficient help in identifications. The pith-feeding larvae belong to only a few species. Poecilosoma candidatum is one of the best known of these. It has been found near Oxford by Professor West-wood, but is rare. The perfect insect is about 1/4in. long. It is black, covered with short pubescence, but certain spots on the head are clay-colour, and spots on the thorax and the edges of the abdominal rings are white. The dull white or yellowish larva bores into the pith during May and June, causing the leaves to wither. It becomes a pupa in the soil, after dropping from the branch. The dead branches should be cut off early, to destroy the larvae in them. The leaf-feeders on Roses among Sawflies are far more numerous than twig-feeders. Among those that devour the leaves, the most destructive species, probably, is Eriocampa Rosae, a small insect, only about 1/8in. to 1/6in. long. It is shining black, with the knees and the feet of the front and middle legs white. The wings are smoky, darker at the base. The larvae are known as Rose-slugs. They are sluggish in habit. The front segments are swollen a little, and humped. The colour is pale yellowish-green, with a dark line down the back; the head is orange. The larvae feed on the upper surface of the leaflets, gnawing away the upper skin, and destroying the leaves, which turn brown. The larval stage lasts about fourteen days or three weeks, and the full-grown larvae reach a length of about 1/3in. They go underground to form their cocoons. The females lay their eggs on the midribs of the leaves, in May. This insect is plentiful both in Europe and in America, in which country it was first described, being named Selandria Rosae by Harris. It is often very destructive to Rose-bushes in gardens.
Watering the plants with infusion of hellebore, or powdering them with sulphur, as is done to destroy Mildew on Roses, are remedies for these troublesome larvae.
Blennocampa pusilla, a Sawfly a little larger than the last, is at times as hurtful; but the larvae have the habit of turning down the sides of the leaflets, and live protected in these retreats. The leaves are sometimes much injured, and the bushes are evidently weakened by this treatment. The larvae are short, stumpy, and green, with the head pale or brown. There are short, spiny hairs on the back. The skin of the sides of the body hangs down in folds. They become pupae in cocoons in the soil, and in May and June Sawflies emerge of a shining black, with yellowish-white knees and feet on the front and middle legs, and grey-brown wings. This species is very common. Emphytus cinctus is another common and hurtful species. It is a little over 1/3in. long. Like the former, the Sawflies are shining black, except that in the female there is a white band nearly round the fifth segment of the abdomen; the hinder legs are partly white, the other four have the greater part of the shins and the feet reddish; the wings are clear. The eggs are laid on the lower surface of the leaflets. The larvae feed on the edges of the leaflets, keeping the hinder part of the body curved over the latter, and, when at rest, they lie curled up in a ball on the lower surface of the leaflets. The body is stout, and tapers backwards. It is dark green above, with the sides light grey, and is sprinkled with small shining white tubercles; the legs are nearly white, and the head varies from yellow to brown. The larvae, when full-fed, usually bore into the branches, and there become pupae; but they form their cocoons sometimes among dead leaves and other rubbish on the soil.
E. melanarius and E. rufocinctus are nearly allied to the last, with similar habits, but are not so numerous as to call for a detailed description. Cladius pectinicornis is also rather common upon Roses in gardens. The Sawflies are a little over 1/3in. in length, and are shining black, with scattered fine grey hairs, and yellowish-white knees and feet, and faintly smoky wings, paler near the tips, with the veins near the base reddish. The larvae lie flat on the lower surface of the leaflets, which they gnaw into holes between the larger leaf-veins. They are flattened, and taper from about the middle towards each end. On each segment are three rows of warts, each of which bears a long brown hair; the head is small. The body is deep green or yellowish-green. The cocoons are spun between dead leaves. There are two broods in the year, the autumn brood passing the winter as larvae in the cocoons.
Cladius Padi, a nearly allied insect, but only half as long, is often plentiful, and is destructive to Roses, as well as to Pear, Plum, Hawthorn, Birch, and various other trees and shrubs. Its larvae also eat holes in the leaves. The cocoons are made in the soil. From two to four broods have been recorded in the year.
The genus Hylotoma, which has three-jointed antennae, and the larvae of which have twelve or fourteen claspers, or prolegs, includes several species that live, as larvae, on Rose-leaves, viz., H. enodis, H. gracilicornis, H. pagana, H. Rosae, &c. Of these, the last-named species is the most destructive, and we shall therefore describe it as a type of the genus as regards habits of larvae. H. Rosae is about 1/3in. or 2/5in. long, and is dull yellow, with black head and antennae and thorax; all the legs are yellow, save that their bases and rings round the feet are black. The larvae are bluish-green, with yellow spots along each side of the middle line, and on the sides are black spots, bearing bristles. The head is black-brown. There are two broods, the insects appearing in May and June, and again in August and September. The females lay their eggs in slits in young branches. The larvae hatch in a few days, and crawl on to the leaflets, which they gnaw from the edge inwards. Fig. 395 shows two characteristic attitudes, that on the left being assumed if they are disturbed. They cast their skin about four times. When full-fed, they creep underground, and there spin cocoons and become pupae. Lyda inanita is the only other Sawfly which we shall mention specially as feeding on Rose-leaves. This insect is black, except a broad, dirty, yellow band lengthwise on the abdomen, yellow markings on head, antennae yellow at their base, and brick-red elsewhere, and legs straw-yellow. The antennae are twenty-one-jointed. The larvae are yellowish-green, with broken red lines on the sides, and a black spot on each side of the first body-ring. Each larva lives in a tubular sack, formed of fragments of Rose-leaves arranged spirally. When full-fed, it leaves its sack (then as much as 2in. long), hanging to the back of a leaf, and burrows underground, there to become a pupa, from which the Sawfly emerges next year.
Remedies. Most kinds of Sawfly larvae can be shaken off the bushes into vessels, or on to sheets, from which they can be swept up, to be destroyed; or the bushes may be sprinkled with flowers of sulphur, or watered with infusion of hellebore or of Paris green. Hand-picking is effectual only if the bushes are few, but is the best remedy for Lyda inanita and Blennocampa pusilla, which live concealed--not exposed, as do the others. It is advisable also to capture the Sawflies, either by using a sweeping-net, or shaking the insects off their favourite perches into some vessel or receptacle. This should be tried only in cloudy weather, as the insects are then quite sluggish, but take to flight readily in sunny weather. It has been found useful to grow flowering plants of Parsley among the Rose-bushes, as the insects congregate on the flowers, and can easily be taken upon them in the sweeping-net. The pupae may be destroyed by removing and burning all loose, dead leaves, &c.; and by removing a few inches of surface-soil, in autumn, with the cocoons. In this way, both those that become pupae in debris, and those that do so in the soil, are destroyed.