Amongst the beautiful beech woods of Hertfordshire, where the timber produced commands a higher price than that from any other station in Britain excepting the Chiltern Hills, the trees are suffering severely. After a careful inspection of many beech woods, I am at a loss to account for the spread of this insect. Usually, in the case of injurious forest insects, the presence of dead and dying wood and the general health of the plantations have much to do with the attack, but this would not appear to be the cause in the case of the beech coccus. Even old and diseased trees do not appear to suffer more than the young and healthy specimens, and at Burnham some of the youngest and fastest growing specimens were by far the worst affected, appearing in parts as if coated with drifted snow. Neither would soil appear to have anything to do with the spread of the insect, as on chalky, sandy and loamy soils, as well as on shale rock, the trees are all more or less affected. I cannot say that unhealthy trees are more liable to be attacked than vigorous ones, for I have observed diseased trees to be sometimes quite free from the coccus, whilst healthy specimens in the immediate neighbourhood were badly infested. This was particularly noticeable on some park trees on two estates that I visited lately; in each instance the majestic boles rose to a height of fully 90 ft. and contained about 100 cubic ft. of wood. At one time I had an idea that beech trees when grown too thickly were most liable to be attacked, but more extensive observations have disproved the hypothesis. By some it has been suggested that the drainage of ground on which the beech is growing will facilitate the spread of the insect by bringing about an unhealthy state of the trees. To some extent this has been noticed at Burnham, and particularly in Gloucestershire, where a lake had been formed contiguous to a beech plantation. In another instance that came under my notice the burrowing of rabbits to an unusual extent was blamed for the appearance of the insect and the gradual death of the trees, the soil in this case being sand and gravel. It is a strange fact, too, that a badly infested tree may be standing amongst others that are perfectly free from the attack. Under a magnifying glass the insect appears of a yellowish colour, irregularly globular in shape, and almost transparent. It is thickly covered over by a secretion from the body, which looks like fine waxen-white threads or cotton wool, which effectually screens the insect from observation. With its proboscis it sucks up the juices, which are readily reached through the thin, smooth bark. When badly attacked, the foliage becomes meagre and has a burnt appearance, then the tips of the branches, and finally whole branches die off. Afterwards the bark becomes dry and cracks, usually longitudinally, falling off in flakes with the death of the tree. The timber of trees that have been killed by the coccus is