Spinach Leafminer: Appearance, Territory, Damage and Life Cycle

Latin Name: Pegomya Hyoscyami

Appearances: At first, the mines are long and thin, but they ultimately grow into an unevenly shaped patch. The larvae are pale, carrot-shaped, and lack legs and a visible head. The adult fly is greyish to brownish in color, hairy, and about 1/4 inch long. Small black to grey flies with yellow patterns are the adults. Long stiff bristles cover the entire body. When mature, the larvae are practically translucent white or yellow in color and about 0.25 inch long. White, cylindrical eggs are laid individually or in small groups and are white, cylindrical eggs.

Host Plants: Early greens may be harmed by the spinach leaf miner, which is a common early-season pest. It targets plants in the Chenopodiaceae family, such as chard, beets, and spinach, as well as weeds like lamb’s quarters and pigweed.

Territory: They are a severe ecnomic threat to many vegetable crop species around the world, and they are a foreign species in Australia.

Damage Caused: The Leafminer is a fly larva that burrows through the layers of a leaf and consumes everything except the epidermis. The first damage appears as a thin, winding ‘mine,’ but over time they spread and develop blotches on the leaves. A pale, white maggot might be found inside the mine.

In most seasons, the damage is minor, and the plants will outgrow it, leaving only cosmetic harm on the early leaves. Damage may be severe in previous years or fields in the same year, and if the plants are attacked early and growth is poor due to weather conditions, the loss may be significant. When eggs or the first little mines are discovered, treat them.

Life History and Habits: The fly spends the winter as a pupa in the soil and emerges in late April and early May. The adult fly then lays eggs on the leaves, and the larvae that hatch proceed to damage the plant.

The little maggots munch into the leaf when the eggs hatch in around 4 days. A leaf may contain numerous maggots. Larvae grow to the point where they fall to the ground and pupate just beneath the soil surface. In 10 to 25 days, adults emerge and begin laying eggs for the next generation. Every year, there are at least three generations. The oblong white eggs are placed in tidy clusters on the underside of the leaves and are less than 1 mm long. If you scout by searching under the leaves, you’ll find them easily. The maggots may go from one leaf to the next in a row. In just a few weeks, they reach full maturity and pupate in the earth.

The life cycle lasts 30-40 days. Each season has three to four generations. Peak activity periods are often mid-late May, late-June, and mid-August.