FIG. 7.-Aspidiotus Juglans-regice (The English Walnut Scale): a, female scale; b, male scale; e, male chrysalis; d, male scales on twig; e, female scales on twiga, b, c, enlarged; d, e, natural size. (From U.S. Dept. Agric.)

FIG. 8. Aspidiotus camellia (The Greedy Scale): a, female scale from above; b, same from below; c, mass of scales as appearing on bark; d, male scale; e, male scales on twig; f, female scales on twig- -e and f natural size; c, considerably enlarged; a, b, d, greatly enlarged. (From U.S. Dept. Agric.)

Scurfy barklouse (Chionaspis furfurus), Fig. 3.
West Indian peach scale (Diaspis lanatus), Fig. 4.
Rose and blackberry scale (Diaspis rosa), Fig. 5.
Euonymus scale (Chionaspis euonymi), Fig. 6.
Beech and Linden scale (Prosopophora sp.).
Willow scale (Chionaspis salicis).

Imported oak barklouse (Asterodiaspis quercicola).

Cottony maple barklouse (Pulvinaria innumerabilis).

Maple leaf scale insect (Pseudococcus aceris).

English walnut scale (Aspidiotus juglans-regia), Fig. 7.
Rapacious scale (Aspidiotus camellia), Fig. 8.

Common plum Lecanium (Lecanium prunastri).

REMEDIES FOR SCALE INSECTS. - Experimental work with remedies for scale insects was begun by the Department of Agriculture in 1880, at a time when Professor Comstock made his extensive investigation of the insects of this group. The recommendations which he made at that time practically focussed upon whale-oil soap. In California he found that this substance, applied at the rate of three-quarters of a pound to the gallon of water and at a temperature of one hundred degrees Fahrenheit, killed every individual of the red scale upon orange. Two years later the remarkable work of Mr. H. G. Hubbard upon the scale insects of the orange in Florida resulted in the systematizing of the work with kerosene emulsions, and demonstrated that no better mixtures can be applied to unprotected scale insects than a solution of the standard kerosene soap emulsion in ten parts of water. Mr. Hubbard's results were widely published, and his mixture remained from that time until two years ago the generally accepted and almost solely used remedy against scale insects. No satisfactory experiments with winter washes were made in the East until the winter of 1893-94. California workers had, in the meantime, however, developed a line of washes based in the main on lime, salt, and sulphur, or lime, sulphur, and blue vitriol, or resin, caustic soda, and fish oil. In the winter of 1893-94 extensive experiments were begun at the Department of Agriculture in Washington, and these California washes were naturally tested at the start. It was found, somewhat to our surprise, that although the evidence in favor of their efficacy on the Pacific slope was not to be doubted, in the East they were practically of no use. By no means all of the scales were killed, and in some

instances such an absurdly low proportion of the insects died that this line of experimentation was soon abandoned. The reason for this extraordinary difference in the efficacy of these washes may be laid partly to differences in the average winter temperature between the two sections, and partly to the great difference in precipitation in the early part of the winter.

Following these early experiments, many other substances, in many combinations, were tested, and, not to worry you with details, the practical outcome has been that for dormant trees affected by practically any scale insect, the best wash beyond all doubt was shown to be whale-oil soap in considerable strength. Some species are more susceptible to the action of the wash than are others. Even against the extremely hardy San José scale, one and three-quarters of a pound of the soap to the gallon of water, put on thoroughly, has proved absolutely effective. It is advised that the applications be made in the autumn after the leaves fall, and again in the spring before the buds burst. Little or no harm will be done if the application be made at even a later date, since in April peach trees in full bloom have been treated with no serious consequences. Experiments on a large scale seem to show that the fall application has occasionally an injurious effect in limiting the amount of bloom the following spring, but the increased vigor of the plant probably more than offsets the falling of the bloom.

The greatest difficulty with the soap washes, and one which must be obviated before uniform results can be hoped for, is in the varying strength and character of the soap used. No two brands of soap on the market are alike, and the differing results which are obtained by experimenters are undoubtedly due in large measure to the character of the soap itself, in connection, of course, with the varying climatic conditions. In addition to securing a good strong caustic soap, one is wanted which, at the strength employed on cooling, will not become a semi-solid or glutinous stringy mass, as do most of the ordinary soaps and also many of the fish-oil soaps of more recent manufacture. The old whale- or fish-oil soap employed in the original experiments could be sprayed in solution at three pounds to the gallon, and this is a most necessary characteristic. It is highly desirable, therefore, that soap makers should be encouraged to undertake the manufacture of a definite brand of soap which can be