Sitona
A genus of small beetles belonging to the family of Weevils. It includes those popularly known as Pea-and-Bean-Weevils, which receive this name because of the harm they do to the Pea and Bean crops, especially in field cultivation. But they also feed on many other leguminous plants, e.g., Clover. In them the beak is shorter than in most Weevils, and projects horizontally. It is flat, except for a slight channel along its upper surface. The antennae are elbowed. The body is oblong, with the thorax a good deal narrower than the abdomen. The beetles are about 1/6in. or a little more in length. Their ground-colour is black; but this is almost always more or less concealed by a coat of ochreous, grey, or rosy scales and hairs. These scales and hairs are apt to be rubbed off, and to disappear after a time. The most hurtful species are S. crinita, the Spotted Pea-weevil, and S. lineata, the Striped Pea-weevil. The former bears ten punctured stripes down the wing-cases, these stripes being alternately dark and light ochreous. The former species is a little smaller than S. lineata, is more grey or rosy than that insect, and has a few dark spots on the wing-cases. Both have the limbs, for the most part, dull-red.
The beetles feed on Peas, Beans, and other leguminous plants, gnawing the young leaves and leaflets from the margins inwards, and, in this way, sometimes completely destroy the crops, if the weather is cold and unfavourable to growth after the young plants have come through the soil. Strong, healthy plants suffer least from them. The life-history of these Weevils has been followed out, within the past three or four years, by Messrs. Hart and Christy. The larvae feed on the roots of Clover, and, it may be presumed, of other Leguminosae. They have been observed of all sizes and ages in the autumn, and many of them live through the winter as larvae, and reach their full size in spring. When full-grown, they are footless, wrinkled, white maggots. They become pupae in oval, earthen cells, 1in. to 2in. below the surface of the soil; and in two or three weeks they emerge as beetles. It would thus seem that the larvae are injurious; but the beetles are far more so. They are apt to remain undetected in their depredations, as, when in danger, they drop at once from the plants to the soil and hide under particles of earth, &c.; but pressure, or stamping with the feet, on the soil around the plants, makes the beetles' come out in swarms. They seem to pass the winter in open ends of stubble, or in any other convenient retreat.
Remedies. The best is probably to make up the seedbed so as to be favourable to rapid and healthy growth of the young plants, thus rendering them able to survive the attacks of the Weevils. For the same reason it is well to water the plants in dry weather. It is recommended also to lay wood-ashes or coal-ashes along the drills above the rows of Peas or Beans, as this favours growth. Rolling the ground brings the Weevils to the surface, and kills many of them. Applications of lime or soot to the wet leaves renders these distasteful to the insects; but the most useful application yet tried is paraffin, in a solution of about two ounces to one gallon of water, with which the plants should be watered.