Elm Tree Destroyer
A. Entrance of Parent Tube.
B. Insect in Tube.
C. An imperfect Tube arrested from want of nourishment.
D. Scolytus Destructor. Natural size.
E. Lateral Tubes with Larvæ, some changing to the Pupa state.
The only remedy is to collect the cone-like excrescences and have them destroyed, except in the case of badly infested trees, which should be cut down and burned.
The Elm Tree Destroyer (Scolytus destructor) is about one-fifth of an inch long, stout and cylindrical, and usually confines its depredations to the elm.
In the beginning of June this beetle bores into the inner bark, where it forms galleries, along the margins of which are laid the eggs. Cutting down and burning badly-attacked trees is the best remedy, but promoting exuberant health of the infested specimens by means of enriching the soil has been attended with promising results.
The Goat Moth (Cossus ligniperda) is most frequently found on the willow, oak, lime and other trees. Being not only one of our largest native moths, but also one of the most destructive, its ravages are much dreaded, the holes or tunnels made by the moth being of large size—large enough to admit the little finger. Filling up the tunnels with a mixture of soot, lime and cow manure is an excellent remedy.
The Lackey Moth (Clisiocampa neustria), so called from the gay colours of the caterpillar, is another destructive woodland pest, eating wholesale the leaves of the oak, elm, beech, poplar and most fruit trees.
In April and May the caterpillars are hatched, when the leaves are just unfolding. They form a nest or web of silken hairs, generally amongst the smaller branches, in which they live during the day, sallying forth in the evening to feed on the tender foliage. Being very plentiful, they are usually difficult to deal with, but hand-picking and destroying the cocoons are the only practicable methods of meeting the evil.
The Winter Moth (Cheimatobia brumata) and the Lime Looper Moth (Hybernia defolaria).—The caterpillars of both these moths are very destructive to the leaves of elms, limes and willows, but particularly to the buds of the apple tree.
When full grown they descend to the ground, where they cover themselves and become chrysalides, from which the moths appear from October to December.
Being almost wingless, it is by no means difficult to prevent their ascending the trees by painting a band of any sticky substance around the stems of the trees that it is expected they might attempt to crawl up.
A. Cossus Moth.
B. Chrysalis from which the perfect Insect has escaped.
C. Cluster of Eggs.
D. Magnified Ovum.
THE GOAT MOTH
The Red Spider (Tetranychus).—In hot and dry summers trees suffer much from this member of the mite family. Limes and poplars, as also many other trees, are greatly injured, the foliage turning to a russety brown colour, and falling off long before the usual time. There are several remedies, such as fumigating and spraying with a solution of soft soap, but none of these are applicable to a plantation of trees, or even a single specimen of large size.
The Thorn Fly (Aphis Cratægi) attacks whole hedges or brakes of Quick, especially those in the nursery border; as a rule, the younger and more healthy plants first fall a prey to its depredations.
Sponging with tobacco water, or almost any of the prescribed solutions will rapidly exterminate the fly; but such work is laborious when a large brake or long hedge of the thorn has to be gone over.
The Cockchafer (Melolontha vulgaris) is usually pretty abundant, and does most damage by eating the leaves of the sycamore, beech, oak, cherry and many other trees. It will also eat the roots of most young trees, but those of pine in particular.
The insect is about 1¼ in. long, and of a chestnut-brown colour on the upper part of the body, while the head and some other parts of the body are of a bronzy green, and thickly covered with yellowish-white hairs.
In April and May the eggs are laid in a hole in the ground about 5 in. deep, and the grubs are hatched in July. They are of a dirty-white colour and much wrinkled. In this state, however, they do but little harm; but, after having changed their skins and remained in a torpid state during winter, come to the surface in spring and eat the roots of almost any plant that comes in their way. They again burrow deeper at the approach of winter, coming to the surface again in spring, and, when full grown, are about 1½ in. long, and almost ½ in. in diameter. The perfect insects do not live more than about twelve days, and are easily known by their heavy, awkward flight towards the evening.
The Laburnum Moth (Cemiostoma laburnella) is fairly abundant—in England, at least; and, in some instances, every leaf of a tree has been eaten almost wholesale by the caterpillars of this pretty moth. The insect is about one-eighth of an inch in length, and three-tenths of an inch across the fully expanded wing. It is of a silvery-white colour.
The greenish-grey caterpillars are about ¼ in. long.
By burning the attacked leaves great numbers of the caterpillars may be destroyed, while, by shaking the trees in May and August, the moths will fly out, and may be caught in a butterfly net.