Leaf Miners

leaf miner in gardenThe name “Leaf Miner” is used to refer to the larval or maggot stage of an insect that feeds upon the leaves and greenery of many valuable garden crops, including lettuce and cabbage, beans and peppers, berries, and a wide variety of flowers and citrus trees and shrubs, among others. While most plants can withstand a great deal of damage and remain quite healthy, the damage from leaf miners can be unsightly and will reduce the saleable value of most crops quite quickly. Continue reading to learn how to organically reduce these nuisance critters before they invade your plants and do noticeable damage.

Need to know…

  • “Leaf Miners” are the maggots of a specific insect
  • Not likely to harm plants unless a large number, but the damage can reduce the value of crops

Dealing with a Leaf Miner Problem

As with any pest problem, the first step to treatment is identification. Adult leaf miners look quite similar to typical house flies. They tend to average 1/10 of an inch in length and can be black or grey in color with yellow stripes and clear wings. Larvae look like tiny worms or maggots, approximately ⅓ inch long, colored green or pale yellow. Eggs can be found laid underneath the surface of the leaf and may appear as tiny raised spots which will hatch within ten days. As leaf miners feed, they create clear, winding tunnels through leaves and other greenery, leaving behind a trail of black fecal matter. The danger to leaves comes from the possibility of bacteria or fungi entering these tunnels, in which case the leaves will turn yellow and fall.

Types of Problems Caused:

  • Leaf Miners feed on leaves
  • Look for winding tunnels through leaves
  • Leaves may yellow and drop if tunnels then become infected
  • Large numbers will decrease hardiness of crop and is a common explanation for less than satisfactory harvest output
leaf miner damage
Damage to leaves from leaf miners

Getting Rid of Leaf Miners

As we always recommend with organic garden pest control, the best method for maintaining healthy crops is to encourage the vitality of your soil, and the life cycles of beneficial insects which help keep the environment in balance. We discourage the use of pesticides, as this will destroy these beneficial insects and will almost surely lead to even more destructive outbreaks down the road.

Monitor your plants closely and crush any tunnels between your fingers to kill any larvae present within. The best way to prevent an overabundance of leaf miners is early detection, so be vigilant. If you spot any infested leaves, pick them and toss in the trash away from the garden.

Maintain the health of your plant by composting and fertilizing as necessary according to the needs of your individual plant. We are here to help with specific instructions for fruits, vegetables, herbs, and more.

Physical remedies such as floating row covers or sticky traps can be utilized as necessary, but bear in mind the individual limitations of each. Row covers are not suitable for crops that require pollination, and sticky traps will not help in the larvae stage. A better alternative may be to purchase beneficial insects such as the parasitic wasp diglyphus isaea. We especially recommend this option for those growing indoors. Botanical insecticides or neem oil (affiliate link) can be used but as a last resort. These will break down faster in the environment than traditional pesticides, but will still repel your beneficial insects and disrupt the balance of your garden.

Methods for Removal:

  • Prevention
  • Maintain healthy soil
  • Compost/fertilize as needed, dependant upon crop
  • Beneficial Insects
  • Parasitic Wasp (commercially available)
  • Crop Covers
  • Early detection
  • Remove any infested or infected leaves immediately
  • Sticky Traps (for flies)
  • Last Resort
  • Botanical Insecticides
  • Neem Oil

Remember that, while leaf Miners are not the worst pest that could visit your garden, too many of them can make your plant susceptible to infection, and severely decrease its vitality. Early detection and prevention through a balance of beneficial insects and healthy soil are key. Let us know if you have any additional questions.
Happy Gardening!