The sluggish adult is found, during May or August, upon kohl rabi and turnips, mustard and charlock, with its wings folded together. The female, by means of her ovipositor, saws small holes in the margin or under side of the leaf, and lays her eggs in these. The larvæ are hatched in from four to six days, and they undergo four moults. The presence of the larvæ can be detected by their cast skins, which remain sticking to the leaves even when the animals themselves, which are often found rolled up on the under sides of the leaves, cannot be seen. The enemy is also known by its way of feeding, for the larvæ keep on the surfaces of the leaves (upper or under surface) and eat out longish holes. As soon as these have reached a certain size, other parts of the leaves or other leaves are attacked. When the larvæ are numerous the holes continually increase in number until only the leaf-ribs are left. The mature larvæ creep into the soil to a depth of from two-fifths to four-fifths of an inch, and spin a small cocoon. The saw-fly emerges either the same or the following year. These insects may therefore appear in May or in August, but in many cases they are seen at only one of these times, either the summer or autumn turnips being attacked, as the case may be. _Remedies_: Fowls and ducks willingly eat the larvæ, and, provided they are not able to do any damage, can therefore be brought into the fields. Strewing with soot has a good effect. It pays to pick off the larvæ from young plants. ORDER 5: =Lepidoptera= (BUTTERFLIES AND MOTHS). [Illustration: FIG. 92.—Head of a Butterfly. A, eye; _Fh_, antennæ; Z, proboscis. ] [Illustration: FIG. 93.—Scales from a Butterfly’s Wing (strongly magnified). ]