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Hawthorn Caterpillars

The Hawthorn, or Whitethorn, is attacked by the Caterpillars of numerous species of insects, considerably over 100 having been recorded as feeding on it; but, among these, only a few do sufficient damage to require a detailed account of their ravages. They belong to various groups of insects, and most of them are hurtful to several other plants; hence, in this place, references will be given to other headings for some of the insects named. Several belong to the Lepidoptera, or butterflies and moths; others to the Tenthredinidae, or sawflies. The more injurious Lepidoptera are as follows: Aporia Crataegi (Black-veined White Butterfly), an insect not unlike a large Cabbage White Butterfly, but with the wing-veins black, and the wings almost semi-transparent and unspotted. The caterpillars, while young, live together in a web spun over the leaves and branches; but, when full-grown, they separate and live singly. They are then bluish-grey, with black head, legs, anal lobes, and spiracles, and three bands on the back, alternating with two yellow-brown bands. The pupae are fixed to the branches. These insects, in some parts of England, are common enough to do harm. Liparis chrysorrhea (Brown-tail Moth) and L. auriflua (Gold-tail Moth) are thick-bodied moths, about 1 1/2in. in spread of wing, white, with a coloured tuft of hair in the tail; and in L. auriflua there are dark spots on the front wings. The eggs are laid on the branches, and are covered with the coloured hairs of the tuft. The larvae live in slender webs among the leaves; they are hairy, with tufts of coloured hairs on tubercles on certain segments. L. auriflua, in particular, is often common and destructive (see Liparis). Looper Caterpillars (see Hybernia and Winter Moth). Hyponomeuta padella (Small Ermine Moth), and one or two other species of the same genus, though small moths, are often so numerous as to do great injury to trees and shrubs. Fig. 171 will sufficiently indicate the appearance of the insect, and of the web spun by the larvae for protection. The varieties of moths in the genus are much alike, their front wings being white or grey, with numerous small black dots; the lower wings are darker, and uniform. H. padella is scarcely 1in. in breadth of wings; the others are slightly larger. The females deposit their eggs on branches, in autumn, covering them with a gummy substance, to protect them. The larvae emerge in spring, and, for a time, feed between the surfaces of the leaves. Afterwards, they eat the epiderm also; and subsequently spin a web in common around new leaves, on which they then feed in safety. They are smooth, have a row of dark spots on the sides, and the head is brown. The nests are often extremely conspicuous. The Sawflies that do most harm to Hawthorn are: Dineura stilata, Eriocampa limacina (E. adumbrata), and Lyda punctata. The larvae of Lyda want prolegs, and feed in a web, spun over the branches. Each larva also makes a special silken case for itself (see Lyda). The larvae of E. limacina eat away the upper surface of the leaves, often stripping it entirely off; and the leaves, in consequence, become marked with brown, scorched spots, or, maybe, completely killed. Frequently, great injury is done by these attacks. The larvae usually feed in groups of three or four. They resemble small greenish-yellow slugs, covered with a slimy secretion, and are commonly known as "Slug-worm." Several cultivated trees are subject to their attacks. Dineura stilata is very similar to the last species in the mode in which the larvae feed; but the latter are uniformly green, have the legs quite visible while on the leaves, and they emit a disagreeable smell. Further information will be given under Sawflies (which see). The best means of prevention, or of cure, in respect to these insects are as follows: Larvae living socially in webs are easily removed and destroyed with the webs. The larvae on the exposed leaves are readily killed by dressing the plants with the powder of Hellebore in water, or by using Paris Green. The foliage of Hawthorn is frequently mined by the larvae of various small insects, chiefly moths, but the plants do not suffer much real injury in this way.