. En vertu de l'irragation fruits Cirtus. Les agrumes, les fruits-culture. 42 TTPTTQ TTPTTTT^r'Q TTMT^T7i :) TROP Tr^* UN^T Tr"T fi O/i dans le développement, ces générations ne sont pas distinctes. Les jeunes sont plus abondants en mai et juin. Dans la Fig. 19 est montré le tronc et les branches d'un arbre infesté par l'orange coussin cotonneuse échelle.. Fig. 19 38. L'échelle coussin cotonneuse est contrôlé par l'Australien et l'Kocbele la coccinelle coccinelle, les formes d'adultes qui sont indiqués respectivement en Fig. 20 (a) et (b). Le § 24 AGRUMES SOUS IRRIGATION 43 coccinelle australienne est un peu moins de

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. Cirtus fruits under irragation. Citrus fruits; Fruit-culture. 42 r'TTPTTQ TTPTTTT^Q TTMT^T7i:) TOO Tr^* A T^Tr»T fi O/i in development, these generations are not distinct. Young are most abundant in May and June. In Fig. 19 is shown the trunk and branches of an orange tree infested with the cottony cushion scale.. Fig. 19 38. The cottony cushion scale is controlled by the Australian ladybird beetle and Kocbele's ladybird beetle, the adult forms of which are shown respectively in Fig. 20 (a) and (b). The § 24 CITRUS FRUITS UNDER IRRIGATION 43 Australian ladybird beetle is slightly less than 1 inch in length and IS oval m shape, as shown by the illustration. It is black in color and has red marks. The larva is longer than the adult, often about i inch in length; it is of a lead-gray color, has- slightly reddish sides, and is often covered with a whitish powder which comes from the egg case of the cottony cushion scale! The female beetle deposits from 150 to 200 eggs in the cottony sac containing the eggs of the cottony cushion scale. The lady- bird eggs hatch in 5 or 6 days and the larvas feed on the eggs of the scale. Following the destruction of the eggs they feed on the scale in all stages. In about 3 weeks they become pupas- the pupal stage is passed in the larval skin on the leaves and limbs of the trees; this stage lasts about a week, and then the mature beetles appear. Copulation soon takes place and other broods are brought forth. The beetles are very prolific and arc very efficient in keeping the cottony cushion scale in check. The beetle feeds on its own kind if the scales become scarce, and on account of this destruction of its own kind it is often necessary to replenish the supply of ladybird beetles. Koebele's ladybird beetle is smaller than the Australian beetle, being only about | inch long. The adults are red and have dark markings; the larva are dark red, and are about I inch long. The female deposits small oblong eggs on the egg sacs of the scal

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