prevented from ascending the stems in spring. And the same happens to those which spin themselves down to the ground on gossamer threads, as many do at least once when moulting, and before they lose the power of spinning such filaments, or get too heavy to descend by them; and both of these transformations usually occur gradually and simultaneously about the time of the third moult or change of skin (Fig. 137).

Patent tar for "grease-banding" is only effective while it remains soft and sticky. Its efficacy is not, however, dependent on its stickiness, but on the fact that one (at least) of the ingredients has a smell so exceedingly repulsive to caterpillars that they will not cross the ring till it becomes hard and dry. And even if an occasional caterpillar may face and cross it, the feet and mandibles get so clogged with the gluey composition that it is unable to feed, and soon dies of hunger. It is therefore essential that the grease-bands should remain sticky throughout the whole of the caterpillar stage of the life of the moth-i.e., for at least six to eight weeks (although good patent tar remains sticky for about twenty weeks or more) without the surface toughening and drying. Throughout Germany it costs about 7s. 6d. per cwt., which is enough for grease-banding about 24 acres on the average, young pole-crops, of course, requiring more per acre than old woods.1

Before grease-banding with patent tar the bark of the stem needs to be cleaned of loose bark, so that the grease may be economised and also made to bite well on to the stem. The stems are cleaned with iron scrapers at about breastheight, a girdle of about 4 inches being cleared, and care taken not to damage the soft inner bark by rough treatment. This should be done in winter and early spring throughout areas known to be infested by moth-caterpillars hibernating under the moss or eggs laid on the stems. About the end of March or early in April the rings of patent tar should be applied before mild weather makes the eggs hatch out or the caterpillars resume breeding. The rings can best be formed with small wooden spuds about 1 to 14 inches broad, and smoothed off with other spuds of equal breadth hollowed to a depth of about 3th of an inch. The crop should first be thinned to remove all superfluous poles or stems likely to favour the breeding of the moths, and to reduce the cost of grease-banding.

Collecting the pupa by hand is only practicable when pupation takes place on shrubs or in bark fissures near the ground, and cannot be carried out on any large scale. If the pupa lie on or in the ground, it is better to herd swine in the woods. They devour smooth-skinned pupa lying under moss (e.g., Pine Beauty and Pine Span-worm), but they will not touch hairy caterpillars.

Eggs can only be collected and destroyed when deposited low down near the foot of the stem, and even then many eggs and clusters of eggs get overlooked. A daub of patent tar is, however, efficacious in killing egg-clusters of species like the Gipsy and the Pale Tussock.

Continental Measures.-How such an exterminative measure is applied on the Continent may be seen from the following description of the means adopted with regard to the Spruce-moth (Liparis monacha) in Bavaria in 1890 to 1892 (Figs. 138-142).

Exterminative Remedies.-When once they occur en masse, no radical measures can be taken against the moths, owing not only to their restlessness during the day, but also to the fact that they cover the trees up to the top. Wherever early measures, however, can be adopted, the destruction of every female means the premature cutting off of about

1 This patent tar (Raupenleim) is manufactured by L. Polborn, 1 Kohlenufer, Berlin S.; Schindler and Mützel, Stettin; J. M. Witzemann, Stuttgart; and various other firms. Its composition is indicated on pp. 71 and 539.

90 in the next, and over 8000 in the succeeding year. It was hoped that by means of electric lights, arranged in the infested localities in front of exhausters, the moths might perhaps be decimated. But though long-continued, the experiments were disappointing; the moths fluttered about in dense swarms within the rays of the light, yet displayed no desire to approach close enough to be brought under the influence of the draught playing into the exhauster.

View in the Ebersberger Forest in 1891, after the clearance of the Spruce-trees that had been killed outright. Only a few Scots Pine remained here and there, as above shown, and these were afterwards mostly blown down by a storm in December 1891.-(The late Prof. R. Hartig of Munich is standing beside stem No. 13).-This illustration exhibits very well the form assumed by Scots Pine when growing in close canopy along with Spruce.

The main remedy lies in placing around the stem (either about 15 to 18 ft. above the ground or else at breast-height) a girdle, composed of a viscous gluey or tarry substance, retaining its stickiness and odour until after the caterpillars had done feeding. The great practical utility of this method rests on the characteristic of the young caterpillars spinning themselves down to the ground on gossamer threads during the period before the second change of skin, after which their fully-developed destructive powers come into play. The re-ascent of the stems being prevented by the rings of patent tar, whose odour they loathe, the caterpillars die of hunger. This method was first employed in 1889 in a small 15- to

Showing how young Caterpillars, after spinning down to the ground, are hindered by the "grease-band" of patent tar from reascending the stem to feed on the foliage.

20-year-old Spruce plantation, which was trimmed of its lower branches and ringed with the patent tar; and as this was found to be successful, similar treatment was also accorded to other localities. In 1890 it found adoption on a much larger scale, and again more extensively in 1891; while in 1892 its application has been extended throughout the whole of the tracts that have been infested on a gigantic scale-the stem of every tree, pole, or thicket-growth of the thickness of a forefinger and upwards being ringed, whilst younger plantations have been isolated. The outlay thus incurred in the State forests of Bavaria alone amounted to £100,000. As practically every caterpillar descends at least once to the ground, and as the majority reach the soil in place of being caught on lower growth, especially in old crops, the results have been that millions of caterpillars perished in 1891 and 1892 under the tar-rings, whilst those that tried to come down the stem before entering the pupal stage also found their way barred, and fell into a sickly state, besides easily falling a prey to the thousands of birds that were naturally attracted to such feeding-grounds, to parasitic insects, and to fungous diseases.

The higher up the stem the girdle is placed the more effectual it is, but also the more

Fig. 141.

expensive. In practice it cannot well be put higher than 15 to 18 ft., somewhat thin patent tar being then used, and the ring being formed by means of a longhandled brush fed from a reservoir above it. The extra expense of high rings is only worth incurring when it is certain that a high percentage of the ova are situated on the lower portion of the stem.

Whether rings of patent tar or glue at breast-height will, or will not, be sufficient to save the crop, depends principally on the species of tree, for, with its sparse foliage and less density of crown, Scots Pine is much easier to deal with than Spruce. Timely adoption of this measure can certainly minimise the evil; but when once the caterpillars swarm in enormous numbers, it can only be effective if aided by natural enemies of the insect, and by fungous disease breaking out among the caterpillars owing to the sickly state engendered by hindrance of their usual daily progress up and down the stem towards the end of June or the beginning of July. Thousands of wooden nesting-boxes have now been hung throughout the coniferous forests in Bavaria to protect and increase starlings (Figs. 132-135).

Diseased Caterpillars (1891) swarming on the top shoot

At Ebersberg (1892) the average cost of forming the rings of patent tar has amounted to about 8s. per acre; the cost of the patent tar was 7s. per cwt. at the factory, and 13s. in the forest; while the labour of ringing the stems cost 7s. per cwt. used. About 40 lb. were used per acre on the whole average, so that the mean outlay per acre was 5s. 3d. for patent tar and 2s. 9d. for labour, or 8s. in all.

Before the operation of applying the patent tar is proceeded with, a thinning out should take place in winter, when all suppressed stems and undergrowth should be cleared away. After that the boles must be cleaned wherever the ring is to be put, so that the semi-viscous patent tar may get a firm hold on the bark. For rough-barked trees like Oak and Pine, this cleaning should be about a span broad, but for smoother-barked species like Spruce, Silver Fir, and Beech, it is sufficient merely to free the part from moss and any scaly bark attaching.

The composition of the patent tar or glue is treated as a sort of secret, but it must be an open one, as some fifteen or sixteen firms supply it at about the same price, 7s. to 7s. 6d. per cwt. at the factory. It consists mainly of wood-tar, resin, wood-vinegar, various oily ingredients, and probably black soap; and it must possess the property of not congealing with late frost, of remaining semi-viscous for over three months, and of not running with heat. It should float on water; if it does not, this proves that mineral ashes have been mixed with it, thereby diminishing its efficacy (see also p. 539).

The ring should be put on thick, but need not be broad, as the caterpillars dislike either the smell or the touch of it so much as to make no attempt to cross over; hence a breadth of to 1 in. and a thickness of to in. is amply sufficient. Owing to its semi-viscosity, the patent tar cannot be put on with brushes, but is affixed by means of special appliances, for it must bite close on to the bark so as not to peel or flake off in places.

Various sorts of apparatus have been invented for putting it on, all of them being more or less like syringes in principle, but the simplest and best method, especially when the ring is formed at breast-height, is to apply the tar with a small narrow wooden spade aboutto in. broad, and to smooth it off with another slightly broader wooden instrument to the required breadth and thickness (see Fig. 142). The formation of the rings must be undertaken early enough in April to be entirely completed by the time the larvæ issue from the ova.

Fig. 142.

Spud and smoothing-stick (about th real size).

Observations on living trees and examination of dead stems have shown that no harm is done to the trees by the use of patent tar, and that it does not penetrate into the cambium to interfere with the normal performance of the functions of the latter, although it partially penetrates and softens the bark immediately below the ring. (Nisbet in Trans. High. and Agri. Socy., 1893, pp. 199-205.)

I. Beetles or Chafers (Coleoptera).

These are the "sheath-winged" insects, so called from the outer pair of wings (elytra) being generally horny or leathery, and serving as a cover to the inner pair or true wings, when these are not in use for flight.

An old-fashioned but simple and practical subdivision of the Coleoptera is the classification of Ollivier and Latereille according to the number of joints found in the tarsi, thus:

4. Heteromera, with first 4 tarsi 5-jointed and posterior pair 4-jointed.

1. The Trimera include few beetles of any importance in British woodlands. To it belong the Lady-birds (Coccinellida), which feed on plant-lice (Aphides), and also the Spanish fly or Blister-beetle (Lytta vesicatoria), rare in Britain, but often destructive in Central and Southern Europe.

2. The Tetramera is the most important class, including the Weevils or Snoutedbeetles (Rhynchophora: subdivisible into Scolytide and Curculionidæ, the latter being larger and having a more strikingly elongated proboscis), the Long-horned beetles (Cerambycida), and the Leaf-beetles (Chrysomelida).

3. The Pentamera include the predaceous Ground-beetles (Cicindelida, Carabida, &c.), the Cockchafers (Melolonthidae), the Saw-horn beetles (Buprestide), and the Clickbeetles (Elaterida).

4. The Heteromera are unimportant to the forester. They include the Oil-beetles (Melöeida) the Churchyard-beetles (Blaps), and the Meal-worms (Tenebrio).