1.—9

10

I have been sometimes much blamed for recommending this method, by persons who asserted that they had thereby killed their trees. It was found on inquiry that in their eagerness they had painted over their trees as if they were painting a house with a good thick coat of oil. The use of kerosene and soapsuds is not attended with so much risk, but its application requires for success a few days of fine weather without rain. I cannot speak positively as to the best proportions for this mixture, but probably they would be as follows: 1 pint kerosene, -Jib. soap, 5 gallons water, to be kept well stirred. The result of the foregoing observations is, therefore, that for the destruction of the apple-scale (Mytilasjns pomorum), or any of the allied bark-infecting scale insects on deciduous trees, the time selected should be midwinter. The trees should be pruned and topped so as to lessen the labour required as far as possible, and they should be brushed over with a solution of kerosene in either linseed oil, whale oil, or soapsuds, For oily mixtures lay them on not too thickly; for soap mixtures, choose fine settled weather. If after application it is found that the eggs under the shields are in many cases unhurt, apply the remedy a second time. It must be borne in mind that it is only the eggs which have to be considered; the female insect at midwinter has finished her career and need not be thought about. The class of scales infesting the leaves, or both leaves and bark of either deciduous or evergreen trees, may be represented by four principal insects in this country —namely, (1). tho camellia-scale, forming a white cottony egg-nest; (2) the black-scale, also on camellias, with other trees, forming no cottony egg-nest; (3) Dactylopius, or the "mealy bug;" and (4) the wattle-scale (Iccryapurchasi), forming large white cottony egg-nests. All of these are generally accompanied by a quantity of the black fungus, noticed under Question 9, which arises from the gummy secretion which they exude, and which drops upon the leaves and there decomposes. Two main difficulties occur here as to all these insects, and a third difficulty as to the last two: First, they are mostly found, when stationary, on the lower sides of the leaves ; secondly, the trees and plants they prefer being generally evergreen, it is not at all easy to reach them when they are on the bark ; thirdly, the two last, Dactylopius and Icerya, are active and vagabond during almost the whole of their lives. The plant most subject to ravage by these insects are: for No. 1, the camellia; for No. 2, the camellia and many other garden shrubs; for No. 3, a large number of greenhouse and hothouse plants ; and for No. 4, the wattle, orange, lemon, pine or fir, gorse, and others. Icerya may, indeed, be looked upon as the most dangerous insect pest in this country. The remedy best adapted for these pests is still the same—kerosene ; but tho application is different. Here we cannot get easily at the insect or her eggs; and, as there are several generations in the course of the year, there is no particular season at which it may be said to be best to attack them. Their habitation being also usually on the underside of the leaf (except in the case of Icerya, which is not particular as to its position), even if we could reach the bark we should do little good; there is therefore a necessity to resort to the application of a liquid remedy by spraying. In a greenhouse, where the windows can be closed, fumigation with tobacco is good against tho "mealy bug" (Dactylopius). In the open air, the only remedy likely to be effective is to spray freely over the infected plants the mixture of kerosene and soapsuds mentioned above. In this operation care should be taken that the liquid should fall on the plant in as fine a spray as possible, so as to be more likely to reach every part, and fine weather should b3 chosen so as to give it tho best chance. It must, however, be observed that the prospects of success depend in very great measure upon the accessibility of the leaves and twigs. There is no difficulty whatever in destroying scale-insects, if one can only get at them. Probably the quantity of kerosene in this case may be a little increased. Note.—The acacia and wattle blight, referred to in Question 7, is, I suppose, Iccrya purchasi, and has been included in tho foregoing remarks. But this insect is probably tho most dangerous of the scales as yet in New Zealand, and owners of infected trees should, in my opinion, adopt a much more drastic remedy than that suggested above. Experience at the Cape of Good Hope and in California, where this insect spread some years ago from Australia, tends to show that it must be fought by strong measures. That experience is summed up in the following ssntences of an American expert, Professor Comstock: "The trees should be watched carefully, and if one is found to be infected it should be destroyed at once. Eemember that no better investment can be made than to burn such a tree, and that no other time is so good as the day it is first found to be infested." II. — Question 8. Fir Trees. The pines most subject, as far as my experience goes, to insect pests in New Zealand are Pinm insiguis, Pinus halepensis, and Finns silvestris (Scotch fir). Two enemies have been observed to attack these : a green aphis, which appeared about Wellington some years ago, but which seems to have departed ; and a brown or black aphis, which replaced the first, and is now vigorously devouring pines throughout tho colony. This insect has been described by me somewhat fully in Vol. xvii. of the Transactions of the New Zealand Institute, 1884, pages 13-16, under the name " Kcrmaphis pini, var. Icevis." The remedy best calculated, I believe, to destroy this pest would be tho same as that for scaleinsects —namely, a mixture of kerosene and soapsuds sprayed freely over the tree. No purely mechanical application can be used on account of the dense foliage. Experience in New Zealand has not yet been sufficient to determine whether or not this aphidian kills the trees. About Wellington a very large proportion^after passing through a more or less violent attack, and indeed in some cases after seemingly dymg,-have recovered. This may be seen easily in the Botanical Gardens. Some trees have certainly dicn, but they have been few ; on the other hand, in Canterbury, as I have been informed by Mr. Armstrong and by tho Hon. L. Walker, very many trees have been killed. Whether this may have been duo to some previous-