Garden Mastery Tips
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Summer 2009 |
Leaf Miners
Leaf Miners annually do a lot of damage to edible leafy crops such as chard, cabbage, celery, lettuce and spinach. They have also been found on beans, peppers and potatoes. So, what do they look like and what can we do about them?
The adult leaf miner is a very tiny – about 1/10th inch long – yellow and black fly. The larvae are pale green or yellow maggots and they live in the surfaces of leaves. They leave a long, curving grayish tunnel as they move among the leaves. They may also leave blotched areas in the leaves.
The adults lay their eggs under the leaf surface, usually on the underside of the foliage. The eggs are white ovals or cylinders. The larvae hatch and feed on the soft tissue of the leaves. After feeding, the larvae will drop off of the leaf and pupate underground or under plant debris. There can be several generations each year.
To prevent infestations of leaf miners, use floating row covers. If you see infested leaves, remove them as soon as possible. To keep the larvae from pupating, using plastic mulch or landscape cloth around your plants should keep them from getting to the ground. Tilling between the rows of your crops will also destroy the pupae.
Wasps are the natural enemies of the leaf miners, so growing nectar or pollen laden plants nearby will attract these beneficial insects. Spraying for wasps may cause an outbreak of leaf miners as you are reducing the presence of the natural predators.
Resources
http://en.wikipedia.org/wiki/Leaf_miner, retrieved June 15, 2009.
http://www.batesnursery.com/information/pests/leafminer.html, retrieved June 15, 2009. This site has photos of the damage caused by leaf miners on leafy crops.
“Desire Under the Jacks” by Ken Druse
Sunset Western Garden Problem Solver, Sunset Books, Inc., Menlo Park, CA, 1998.
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