Spinich Leafminer- Identification and Management

The adult fly appears in early to mid- May after overwintering in the soil as pupae. It is a about 5 mm long and are gray in color. The adults can be seen flying near the ground between the plants. The females deposit eggs singly or in rows of two to five side by side on the underside of the leaves. In as little as three days but more commonly in four to six days the tiny legless, white to yellowish maggots hatch from the eggs and work their way into the leaf tissue. The maggots feed between the upper and lower leaf surfaces of the host plants mining out the tissue in between. It is not unusual for several larvae to be in the same leaf. As the maggot grows and continues to feed, the mines, which are at first thread-like, become blotch-like and are easily seen on the infected leaves. The larvae are full-grown in 7 to 16 days when they drop to the ground and burrow a few inches into the soil to pupate. Two to four weeks later the adult flies emerge and will soon lay eggs for another generation. In New York you can expect three to four generations each year.
Management- a preventive spray schedule beginning when the spinach is two true leaves and repeated every 7 days. Remove wild hosts like lambsquarter, nightshades, chickweed, and plantain. Deep plowing in the spring can reduce the overwintering population by burying existing pupae. In smaller stands, infected leaves can be picked before the maggots drop to the ground. Removing and destroying these infected leaves can lessen the leafminer pressure
-Ray Range


Upcoming Events
Vegetable Pest and Cultural Management Field Meeting for Auction Growers -- Ontario Produce Auction

July 15, 2025
Stanley, NY
This evening meeting will demonstrate pest management in fresh market vegetables in both field and greenhouse (high tunnel) vegetables, primarily for those growing for wholesale auction. A hands-on demonstration of weed, insect and disease identification in vegetables including management options. Details on each topic will focus on field observations at the farm.
Orleans Summer Vegetable Meeting, 2025

July 16, 2025
Waterport, NY
Meeting themes are pest management in a wide array of produce and best practices for pesticide use. Professor Brian Nault will cover allium leaf miner and thrips in onions, garlic, and leeks, and discuss insect challenges in other crops. Bring your questions! We'll also have a field walk that includes high tunnel tomato and cucumber.
DEC credits available: 0.5 in CORE plus either 1.25 in 1a and 23, or 0.75 in 24.
Vegetable Pest and Cultural Management Field Meeting for Auction Growers -- Finger Lakes Produce Auction

July 18, 2025
Penn Yan, NY
This evening meeting will demonstrate pest management in fresh market vegetables in both field and greenhouse (high tunnel) vegetables, primarily for those growing for wholesale auction. A hands-on demonstration of weed, insect and disease identification in vegetables including management options. Details on each topic will focus on field observations at the farm.