If your lawn has large brown spots that can come off as if they were patches, it means that the worm larvae have damaged it. These are the Japanese beetle larvae. They are winter dormant insects that lay their eggs around mid-July. In August, the larvae begin to move towards the surface of the lawn, and eat the roots of the grass. To prevent this from happening, you should treat the affected area immediately after the beetles have laid their eggs.
Steps
Method 1 of 2: Preventive Treatment
Step 1. Keep the grass high
Beetles do not like to lay eggs if the grass is not well cut, so if you keep the lawn at least 5 cm high, you help prevent the formation of larvae.
Step 2. Sow the lawn
If you do this in the spring and fall, the grass becomes too thick to be attractive to most beetles.
Step 3. Fertilize your lawn
Fertilize it in both fall and spring. If you can, leave a layer of dead leaves on top of the lawn for the winter.
Step 4. Water sparingly
The eggs of the larvae need moisture to hatch. If you have to water your lawn, water it heavily once in a while rather than just a little every two or three days.
Step 5. Treat your lawn
In the first two weeks of July you should spray insecticides containing imidacloprid or halofenozide. These chemicals poison the larvae and kill them as the eggs hatch. MERIT® GREEN is one of these products.
Step 6. Apply the insecticide following the directions on the package
Step 7. If you want a more biological solution, you can try:
- Paenibacillus popilliae. It is an environmentally safe bio-pesticide that kills Japanese beetles. It is necessary to apply it in the spring, summer and autumn for two years. This helps ensure that the lawn remains "infected" and will remain so for at least ten years. Please note that some larvae are not treatable with this product, and require an application of Merit.
- Nematodes. These are small worms that release deadly bacteria into the soil for the maggots in the lawn.
Method 2 of 2: Remedies
Step 1. Do the treatment in the spring (March to mid-May) and autumn (from the beginning of September to the end of October)
- For treatment in the fall, a product like Dylox is more effective.
- Carbaryl and trichlorfon are effective in both seasons. However, the larvae stop feeding in late May, when the treatments are no longer effective.
Advice
- Japanese beetles lay their eggs only in sunny areas.
- The larvae not only do damage to the lawn, but many animals feed on it. If you don't get rid of the larvae, you will likely find that other animals such as skunks and raccoons may be tempted to come to your garden.
- Merit is effective for three months. Resist the temptation to apply it too soon.
Warnings
- Follow all directions on the package when applying a lawn product.
- Make sure you add water to the product.
