Common name: Diamondback moth
Scientific name: Plutella xylostella
Synonyms: DBM, Plutella
Broccoli, cabbage, cauliflower, other members of the crucifer family
Newly hatched larvae mine tunnels in the leaves. As they grow older, the larvae feed on the undersides of leaves but do not eat the veins, leaving the surfaces untouched, resulting in the 'window effect'. Larvae make irregular holes, tunnel into the cabbage heads preventing further development. In broccoli and cauliflower, DBM feed on the leaves and not on the flower heads.
Eggsare tiny, ovate-shaped, and yellowish-white in color. These
are laid singly or in groups of 2-3 along the veins in the upper and lower leaf surfaces. The eggs hatch in about 5-6 days.
Larvae are pale yellowish-green to green covered with fine, scattered, erect hairs and with a forked posterior end. Mature larvae are cigar-shaped and about 12 mm long. The larval period lasts for about 10-21 days. DBM larva is easily identified because it can wriggle violently backwards when disturbed then drops from the plant suspended by a silken thread and finally climbs its way back up and continues feeding.
Pupae are delicate, white open-mesh cocoons that are attached to the leaves, stems or seedpods of the host plant. Pupae are light green but become brown as the adult moth becomes visible through the cocoon. The pupal stage lasts from 5-15 days depending on the environmental conditions.
The adult moth is approximately 8-9 mm long with a wing span of 12-15 mm. The moth folds its wings over the abdomen in a tent-like manner when
immobile. The wing tips are fringed with long hairs. Adult females can lay an average of 160 eggs during their life span of about 16 days. Egg laying occurs at night. The greatest number of eggs is laid the first night after emergence and egg laying continues for about 10 days. In the field, moths will fly up out of the plant canopy when disturbed.