GARDEN PESTS IN NEW ZEALAND 



Leaf-rollers are easily controlled by the arsenical sprays used against 

 codlin moth, but these sprays must be continued into the late summer 

 after their need against codlin moth is past. 



DIAMOND-BACKED MOTH (Plutella maculipennis). - - The cater- 

 pillars of this moth (Fig. 10, 4) are commonly found attacking the 

 leaves of cabbages, rape and other cruciferous crops and weeds. These 

 caterpillars are small and greenish, and, if disturbed, suddenly drop 

 suspended by a silken thread attached to the plant. The damage they 

 do is very often extensive, considerable areas of the foliage being 

 devoured. When fully developed, each caterpillar spins a silken cocoon 

 on the under side of the leaf, and there transforms to the pupae, from 

 which a moth eventually emerges. The insect is small, narrow, and has 

 a light-coloured, diamond-shaped marking along the back. The moth is 

 nocturnal, and shelters amongst the denser foliage during the day; it 

 emerges at night, and lays its eggs upon the leaves. The life-cycle from 

 eggs to adult occupies some 36 days, more or less, according to the 

 season, and there may be six or seven generations during the year. 



In control, an important point to note is that the diamond-backed 

 moth breeds upon cruciferous weeds watercress, shepherd's purse, and 

 hedge-mustard as well as on the old plants of a crop left in the 

 ground; it is from such places that infestation of future crops arises, 

 and the clearing up of such breeding places should be given close atten- 

 tion. Under garden conditions, control can be secured by spraying the 

 plants with arsenate of lead (to which a spreader must be added in the 

 case of cabbage), which should be done especially when the plants are 

 young. 



KOWHAI MOTH (Mecyna maorialis). The caterpillar of this native 

 moth sometimes becomes epidemic, when it does considerable damage 

 to kowhai, broom, lupins, and sometimes clover. The caterpillar, which 

 measures about an inch when mature, is of a greenish colour, having 

 rows of black tubercles with white centres along the sides, and a double 

 TOW of white spots along the back ; from the black tubercles black bristle- 

 like hairs arise. The caterpillar spins a silken cocoon, in which it 

 pupates. The moth is comparatively small, the fore wings being 

 yellowish-brown with darker markings, and the hind wings orange-yellow 

 with a blackish border. There are at least two broods of caterpillars 

 annually: the first in the spring, and the second during autumn. 

 Arsenate of lead will give effective control on garden legumes. 



CUT-WOK MS. This term is applied to the caterpillars of a number 

 of night-flying noctuid moths; these caterpillars are smooth-bodied and 

 rather worm-like, in some cases measuring from one and a-half to two 

 inches in length when full grown. They feed at night, and their method 

 of attack is characteristic in that they nip off young plants close' to the 

 ground (Fig. 10, 5), so that the latter fall over, when they are devoured 

 by the caterpillars; this habit has given rise to the name "cut-worms." 

 I)uring the day the cut-worms are to be found curled up in the ground 

 close to the plants they have been attacking. The moths of these cater- 

 pillars are rather stout-bodied, and measure about three-quarters of an 

 inch long. One of the commonest species is the cosmopolitan greasy- 

 cut-worm (Agrotis ypsilon). 



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