Melanchra persicariae L Dot moth

The polyphagous larvae of this generally common moth attack various herbaceous plants, including beet, brassicas and potato, and are sometimes minor pests in allotments, gardens and nurseries. The larvae feed voraciously and, if numerous, can cause significant defoliation.

BIOLOGY

Moths occur mainly from June to August and deposit their eggs singly or in untidy batches on the leaves of various plants. The eggs hatch about 8 days later. Larvae feed until the autumn and then pupate in flimsy cocoons formed in the soil. Adults emerge in the following year.

DESCRIPTION

Adult 38-48 mm wingspan; forewings bluish-black, with a prominent, white reniform stigma; hindwings greyish but whitish basally (Fig. 323). Egg hemispherical, ribbed and slightly reticulated, whitish-green becoming pinkish-brown. Larva up to 45 mm long; body pale brown or pale green, with a white line along the back and darker V-shaped markings that are particularly obvious on abdominal segments 1, 2 and 8 (these segments also noticeably humped); head pale brown; prothoracic plate brown or green, with three white lines (Fig. 324). Pupa 22-24 mm long, chestnut-brown; cremaster with two short, divergent spines.

Fig. 323 Dot moth, Melanchra persicariae (x3).

Fig. 324 Larva of a dot moth, Melanchra persicariae (x2).

Mesapamea secalis (L.) Common rustic moth i^liilsaJiffiottaitaTlsaiil^aaiH^ aaa stypi cfaM My-pBsf cieui ilf

Fig. 324 Larva of a dot moth, Melanchra persicariae (x2).

Mesapamea secalis (L.) Common rustic moth i^liilsaJiffiottaitaTlsaiil^aaiH^ aaa stypi cfaM My-pBsf cieui will readily transfer from ploughed-up grasses to young cereal plants, especially barley, oats and wheat. Each larva also typically invades several shoots during the course of its development.

BIOLOGY

The moths occur mainly in July and August, and deposit their eggs on grasses and cereal plants. The larvae feed from autumn onwards. They typically burrow singly within the lowermost f Ocm of a shoot, usually feeding with the head directed downwards. As tissue is destroyed, and the shoot becomes filled with frass, the larva invades another shoot. Larvae are fully grown in the following spring. They then pupate in the soil, and the adults emerge several weeks later. There is just one generation each year.

DESCRIPTION

Adult 30mm wingspan; forewings brownish-grey to dark brown, often with a pale reniform stigma and paler areas along the hind i:argin and between the stigma and the la; ral margin; hindwings pale bi ownish-grey. Larva up to 25 mm long; body pale green and shiny, with a pair of often indistinct purplish-red ion-gitudinal stripes along the back; spiracles dirty whitish; head ]_ale yellowish; prothoracic plate and anal plate greenish to light brown (Plate 15e).

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