RASPBERRY BUD MOTH

New Zealand Journal of Agriculture, Volume 74, Issue 1, 15 January 1947, Page 63

RASPBERRY BUD MOTH

A DESCRIPTION of the life history and habits of the raspberry bud moth (Carposina adreptella Walker) is contained in this article by J. O. Anderson, Orchard Instructor, Masterton. Where damage may be looked for in the canes and methods of combating the pest are also described.

THE raspberry bud moth is between i and jin. long, and light to dark brown or grey in colour, the lighter forms showing darker spots. On each forewing are two conspicuous raised tufts.

The egg is spherical, less than half a pinhead in size, with a series of forked spines at one end. At first it is yellowish-green, changing to yel-lowish-gold. On first hatching the caterpillar is a cream colour except for the dark head. When fully grown it is about fin. long, the colour being variable and probably depending on the food. Eggs are placed singly or in clusters in crevices between leaves in a bud, or sometimes on the under or upper surface of the leaves. Each female lays up to 200 eggs. At the beginning of April these hatch in five days or less; at the end of April and beginning of May the period increases to 13 to 19 days and in July to 21 days. On emerging the young caterpillar bores into the bud on which the egg has been laid or wanders about till it finds a bud, leaf, or fruit on which to feed. Both terminal and lateral buds are attacked. Where the terminal bud of a succulent shoot is infested the caterpillar frequently tunnels for 3 or 4in. down the shoot. In the spring when plant growth is rapid the sawdust-like refuse from the borings at once indicates the presence of a caterpillar, and under such conditions it is likely that it passes its whole larval life in one shoot. In other cases • the hearts of the buds, particularly the lateral ones, may be eaten out. Caterpillars found wandering on the outsides of the canes are probably migrating to fresh buds. In . winter dormant buds on the canes are the only, succulent parts of the

plant, and at this time of the year caterpillars in all stages are found in H them.

Pupation probably occurs in a silken cocoon in the soil. Length of the pupal period varies from 2 to 6 weeks, being longer in winter. The eating of buds and the borings in the shoots are the characteristic

damage done by Carposina, but in the autumn caterpillars have- been observed to feed on the leaves of water shoots or suckers. Usually the under surface of the leaf is destroyed, and when feeding in this position,caterpillars shelter beneath webbing. Damage to buds and shoots results in destruction of the growth which would bear the fruiting laterals in the current and subsequent seasons. A severe infestation may result in the canes being stunted, malformed, and fewer in number.

. It is considered that a severe infestation is usually built up over years and is not caused by an influx of moth from an outside source, such as an area of neighbouring blackberry.

It is advisable to prune the bushes as early in the autumn as possible, as this will destroy a large number of caterpillars in the tops and remove much of the more succulent tissue on which they could continue to breed. If pruning is delayed, there is no obstacle to migration from the tops to buds on the lower canes which will be retained after pruning. All primings should be removed and burnt with as little delay as possible. Spray with lead arsenate (21b. in 100 gallons of water) at green tip and again at open cluster. After the crop is harvested spray again in February and a fourth time 3 or 4 weeks later. If it is felt that a treatment is. required when the fruit has set, a derris dust or spray may be used.

The data on life history is taken from an article on this insect by Miss F- J. Jeffreys in the New Zealand Journal of Science and Technology, Volume 21A (1939), pages 114A-125A.