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Leafminers attack all kinds of plants, from vegetables to fruits, flowers, trees, or shrubs, although each species of leafminer usually feeds on only one or two types of plants. In pines and other conifers, the pests are called needleminers.
Another way of naturally killing leaf miners is to use neem oil. This insecticidal oil affects the leaf miner’s natural life cycle and will reduce the number of larva that become adults and thus the number of eggs that the adults will lay.
How Serious Are Leaf Miners? These pests cause a variety of damage, including pale blotches and tunnels on plant leaves as the larvae feed. However, the damage is cosmetic and does not cause serious injury to most plants. Leaf miners cannot bite or harm humans.
Pick off and destroy badly infested leaves in small gardens. The more healthy the plant, the less chance that leafminers will hurt it. Maintain plant health with organic fertilizers and proper watering to allow plants to outgrow and tolerate pest damage. Keep your soil alive by using compost and other soil amendments.
To make white oil, you will need a spray bottle for treating your plants with the all-natural concoction, preferably one that holds 500 mL, 1 teaspoon of vegetable oil, and one teaspoon of dish soap, and just under 500 mL of water. A light coat of white oil is all you need to keep the leafminers at bay.
Apply floating row covers to the plants during April to May. Controlling infested weeds, especially lambsquarter, may help in control. Rotate crops from one year to the next so they are not planted in previously infested areas. No spray is advised on beets grown for leaf tops.
A: There would be no harm in accidentally eating a leaf miner larva from your spinach leaves. This is also true of other insects that eat garden plants, such as aphids or caterpillars; you’d simply digest them.
Adult leaf miners look like small black flies, but it is not these flies that do to your plants directly. When these larva begin boring their way through the leaves of your plants, they will leave yellow, curvy lines in their wake. The insects may also leave unsightly blotches and spots on your plants’ leaves.
Leafminers are the larval stage of a variety of insects. The female adult lays its eggs inside or on the underside of the leaves. When the eggs hatch, the outside larvae tunnel into the leaves to feed for up to 3 weeks, creating the tunnel-like appearance often seen on foliage.
Some Background. Leafminers are pests which tunnel through the mesophyll of leaves creating distinctive and unsightly squiggly patterns. They are, collectively, mostly comprised of members of two insect orders: Lepidoptera (moths and butterflies) and Diptera (flies).
If you notice leafminer damage on foliage, thoroughly apply Spinosad (Monterey Garden Insect Spray) to all plant surfaces. Once ingested, spinosad stops larvae from feeding and they will die within 24-48 hours. Repeat applicatons 2-3 times throughout the growing season if damage persists.
Clean up any infected leaves on the ground. Spray with 1 tablespoon of baking soda and 1 tablespoon of light horticultural oil or dish soap mixed into 1 gallon of water. You have leaf miners, tiny worms that tunnel inside the leaf.
Application of bacillus thurigiensis, also known as BT, can help with some larval issues as well. Available as a powdered form (Garden Dust) or a spray form (Monterey BT), this bacteria will poison leaf miner larvae if they come into contact with it.
Spray with horticultural oil to deter the moth from laying new eggs. The oil won’t kill the larvae which is why it’s important to remove any infested growth. Spray first thing in the morning to avoid spraying beneficial insects which are less active at this time. This also reduces the chance of burning foliage.
Leaf miners cause damage to plants both directly and indirectly. The most direct damage is caused by the larvae mining the leaf tissue, leading to desiccation, premature leaf-fall and cosmetic damage. In (sub-)tropical areas this can lead to burning in fruit such as tomato and melon. Loss of leaves also reduces yield.
Products labeled for use on citrus that contain Spinosad are a low toxicity option for control of this pest and can be used at any time in the season. Start spraying when a new flush of growth emerges and the first signs of leaf miner damage are found and repeat sprays every 7-14 days.
Overall, neem oil is safe around humans and children so long as you do not ingest it. If ingested, neem oil can induce vomiting and drowsiness. As a reminder, neem oil contains mostly glycerides and fatty acids.