Worms Inside Spinach Leaves

Leaf Miners

• Leaf miners, also known as spinach leaf miners in the case of spinach infestations, are 1/4 inch long flying insects that are dusty gray- or black-colored. These flies often have yellow markings on their bodies. They land on spinach leaves, puncturing the surface of the leaves to eat and lay eggs. The eggs are laid inside the leaves and hatch into worm-like larvae that are white or yellow in color. These larvae are the worms you see inside spinach leaves, as they feed and make distinctive, discolored tunnels along the inside of the leaves. The larvae eventually emerge, pupating and becoming mature flies on the surface of leaves or soil below.

Damage to Plants

• The characteristic trails left inside spinach leaves infested with leaf miners are unappealing visually and make the leaves unappetizing when harvested. While the leaf miners inside the leaves often only leave cosmetic damage, the openings in the leaves make the entire spinach plant susceptible to disease that could kill the entire crop. The adult flies often dehydrate the leaves they feed on continuously, destroying those leaves and leaving seedlings they feed on damaged to the point of stunted growth or death.

Treatment

• Treating leaf miners on spinach should be done as soon as the pests are discovered inside leaves. Use of pesticide sprays are effective at killing and repelling the adult flies as well as their offspring. These sprays must be labeled safe for spinach, effective against leaf miners and should be used according to label instructions. Organic spray options are available. Other methods, such as manually removing and destroying infested leaves or introducing beneficial insects, such as parasitic wasps, are also effective at controlling leaf miners.

Prevention

• Examine plants regularly, even as seedlings, for evidence of leaf miner activity. Remove infested plants if possible to prevent the spread of leaf miners to other plants. Practice crop rotation -- planting your spinach in a different spot each year -- to avoid infestations of leaf miners that may have survived in the soil where you last planted spinach. Treat soil for leaf miners prior to planting your spinach crop and place a protective covering over the plants such as fine netting or well- anchored floating row covers. Leave the protective covering over the plants until harvest.