. The imported cabbage-worm (Pieris rapæ Linn.) [microform]. Pieris rapae; Agricultural pests; Arteogeia rapae; Chou; Cabbage; Ennemis des cultures. The caterpillars or larvae, as they are sometimes called, having completed their feeding, which they usually accomplish in from two to three weeks form chrysalides or pupa which are at first pale green, but gradually assume a brown shade of colour. These pupae are about H >nch in length, and may be found, suspended by silken threads, on the leaves of the food-plant on buildings, or on any con- venient solid object in the vicinity. During the s
. The imported cabbage-worm (Pieris rapæ Linn.) [microform]. Pieris rapae; Agricultural pests; Arteogeia rapae; Chou; Cabbage; Ennemis des cultures. The caterpillars or larvae, as they are sometimes called, having completed their feeding, which they usually accomplish in from two to three weeks form chrysalides or pupa which are at first pale green, but gradually assume a brown shade of colour. These pupae are about H >nch in length, and may be found, suspended by silken threads, on the leaves of the food-plant on buildings, or on any con- venient solid object in the vicinity. During the spring and summer, only from one to two weeks are passed in the chrysalis stageâa stage which is entirely dormant. Then the adult white butterflies appear, to continue the life-history as before. In the autumn, however, the last pupae to form remain dormant all winter, and these chrysalides are the ones which give rise to those butterflies seen so early in the spring. As a rule, three generations occur in a single year, and they overlap so considerably that eggs, larva;, pupae, and adults may at times be found rbrjrmlU of Imported cahoage-butterfly: natural â Ise. (After Britton and Lowry.) ' Control Measures. The worm, larva, or caterpillar stage is the only period in the life-history of this insect which is amenable to treatment on a commercial or practical scale. It is clearly a leaf-feeding caterpillar which freely devours great portions of the leaf-surface. It can, there- fore, be controlled by an application of an arsenical which it takes directly into its stomach while in the process of feeding. Arsene*- of lead represents the most suitable and economical arsenical to use. The only question that is liable to arise is, " What eflfect will poisoned cabbage have on the human system? " The answer is, " No effect, if arsenate of lead is used in normal and judicious quantity, and. Please note that these images are extracted from scanned page
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Keywords: ., bookcentury1900, bookdecade1910, booksubjectagricul, bookyear1918
