FIG. 1. PEACH TREE SEVERELY INJURED BY THE SAN JOSÉ SCALE After Britton, Conn. Agr. Exp. Sta., Bul. 135 FIG. 2. A GROUP OF SAN JOSÉ SCALE OF DIFFERENT AGES After Lowe and Parrott, N. Y. Agr. Exp. Sta., Bul. 193 have reached Virginia from New Jersey, where it had been scattered by means of nursery stock shipped from the San José Valley in 1886 or 1887. The infested nurseries in New Jersey continued to ship nursery stock to all parts of the United States until investigations were made in FIG. 3. ADULT FEMALE SAN JOSÉ SCALE AND YOUNG-FEMALE SCALE AT LEFT-ALL HIGHLY MAGNIFIED After Lowe and Parrott, N. Y. Agr. Exp. Sta., Bul. 193. 1893 and 1894. Thus many sections throughout the United States became infested, especially in nursery and orchard districts. The occurrence in Tennessee In Tennessee San José scale first made its appearance in the eastern part of the State, in Roane County, at Harriman, where it was brought in on nursery trees during 1891 or 1892, yet it was not discovered until 1896.* At this time many trees were found in a highly infested condition. Scale was found next in Claiborne County, near Cedar Fork, in 1897. The following year specimens were received by the Experiment Station from another section of the same county, at Tazewell. In less than a month afterward scale was found in Washington County, at Austin Springs. These scale insects were on trees that FIG. 4. ADULT FEMALE SAN José SCALE-HIGHLY MAG NIFIED FIG. 5. MALE SAN JOSÉ SCALE After Lowe and Parrott, N. Y. Agr. Exp. Sta., Bul. 193. had been purchased four years previous from a New Jersey nursery. Habits and life history Perhaps the worst feature of an attack of San José scale is the difficulty of recognizing the insect, due to its size and color; it is about 1-16 of an inch in diameter when mature, and in color it resembles the bark of tree or plant infested. If there is a very bad infestation an ashy-gray appearance is noticeable; again one may determine the presence of scale by crushing many of them, when an oily appearance is noticed. If a female scale be carefully turned over with a knife or a pin, there will be found underneath a flat, yellowish insect, looking very much like a small piece of rich butter. It has no legs, no wings, no eyes, no antennæ (feelers), nor a distinct head, but it does have a long, thread *Univ. of Tenn. Agr. Exp. Sta. Bulletin, Vol. 10, No. 4. like sucking proboscis, with which it bores through the bark of trees into the young, growing wood and draws out the sap. In April (earlier in advanced seasons) the adult female begins to give birth to living young, continuing to do so for about six weeks, after which she dies. The young scale has legs, antennæ and eyes; it moves about over the twigs for some hours, then settles down and begins to push its mouth parts slowly into the bark to the sap beneath. A scale-like covering now begins to be formed, coming from all parts of the body and looking at first like waxy filaments or threads, which later fuse together, making, with the cast skins, an entire covering over the insect. All young San José scale look alike in size, color and shape until the first molt, about twelve days after birth, but from then on there is a very great difference. The male scale, which is smaller, is now elongate, while the female scale is circular, or nearly so, both sexes losing legs and antennæ, and the female her eyes. In from 24 to 26 days from birth the male comes from under the scale in the form of a minute and extremely delicate two-winged, fly-like insect. FIG. 6. ADULT FE- After Lowe and Parrott, It takes the female about thirty days to develop fully. From thirty-three to forty days from birth she gives birth to a new generation. Each female is sup posed to produce 200 male and 200 female young; this being so, and counting four generations in a season, there will be produced, according to Dr. L. O. Howard, 3,216,080,400 male and female scales from one progenitor in a year.* In Tennessee, where there are at least five generations or broods each year, the above number is greatly increased. Thus it is easy to understand why a slight infestation, if un- FIG. 7. ADULT FEMALE SAN JOSÉ SCALE treated, soon becomes TURNED OVER, SHOWING LEGLESS AND bad. If the scale are alWINGLESS INSECT lowed to increase unmo After Alwood, Va. Crop Pest Com., Bul. 45 *Bureau of Ent., U. S. Dept. of Agr., Bul. 12. fested districts. When once introduced it is only a short time before multitudes occur. When the scale are young and active they crawl upon the feet and legs of birds and insects and are thus transferred from tree to tree. Men and teams at work in an infested orchard or nursery may also con FIG. 9. ADULT MALE SAN JOSÉ SCALE-HIGHLY MAGNIFIED Dept. of Agr. |