Buzz
These are small, white, worm-like larvae of certain insects, particularly the Japanese beetle, the watermelon beetle, and the European chafer. As they grow, these larvae feed on grass roots, causing the grass to die and forming brown patches on the lawn. To effectively eliminate beetle larvae, it is crucial to identify the specific type of larvae you are dealing with, as this will determine the appropriate eradication method.
Steps
Eliminate Larvae Using Natural Methods
Look for signs of larvae. One of the primary indicators of larvae presence is irregular brown patches on the lawn or dead grass, though this can also result from other causes. If you suspect larvae are the issue, look for additional signs, including:
- Holes in the lawn dug by birds and other animals hunting for larvae
- Patches of grass with missing roots
- A spongy feel when touching or walking on the lawn
Locate the larvae. Once you have evidence of larvae presence, the next step is to inspect your lawn to find them. Use a small shovel to dig up one or two patches of dead grass.
- Dig a small area (30 cm x 30 cm) where dead grass meets healthy grass.
- Dig about 5 cm deep.
- Look for C-shaped grubs with legs near their heads.
- If you spot these grubs, it confirms the presence of larvae.
Determine if you need to eliminate the larvae. Even if you find larvae on your lawn, the need to eradicate them depends on their quantity. A few larvae may not harm your lawn or affect its appearance, especially if the grass remains healthy.
- No action is needed if you find fewer than 5 larvae in a 30 cm x 30 cm area.
- If you find between 5 and 10 larvae in the same area, treatment is only necessary if the lawn is not thriving.
- Regardless of the lawn's condition, you must eliminate the larvae if you find more than 10 in a 30 cm x 30 cm area.
Use beneficial nematodes to eliminate any type of larvae. Scientifically known as Heterorhabditis bacteriophora, these tiny parasitic worms invade larvae and release bacteria to kill them. However, this is a long-term solution, and it may take up to 3 years for nematodes to fully control the larvae problem.
- For best results, apply in the evening and water immediately afterward.
- These worms need to enter the larvae's bodies to reproduce, so you must choose between nematodes or chemical pesticides.
- They are sold as Hb nematodes and can be purchased at garden stores, through ads, or online.
Use bacterial spores to eliminate Japanese beetle larvae. Bacillus popilliae is a bacteria used to kill Japanese beetle larvae. Available in spore form, it comes as a powder that can be sprinkled on the lawn. Like nematodes, this is a long-term solution rather than a quick fix.
- You can mix this product with water and spray it on the lawn or apply it as a dry powder.
- Similar to beneficial nematodes, you must choose between Bacillus popilliae or chemical pesticides, as the bacterial spores won't reduce larvae numbers effectively otherwise.
- Japanese beetle larvae can be distinguished from others by their pointed tails, unlike most larvae, which have rounded tails.
Seed and fertilize your lawn in the fall. Beetles typically avoid laying eggs in thick, tall grass. By seeding and fertilizing, you can repair damage caused by larvae and prevent beetles from laying more eggs.
- Clear dead grass from brown patches in spring and fall. Water the area, then spread new grass seeds over the dead spots.
- After reseeding, apply fertilizer to revive dead patches and encourage new grass growth.
Let the grass grow taller. Beetles prefer not to lay eggs in tall grass, so allow your lawn to grow higher than usual as it begins to recover.
- Maintain a grass height of around 5 cm. Adjust your lawnmower blade to a higher setting to achieve this during mowing.
Avoid overwatering. A simple way to prevent your lawn from becoming a breeding ground for larvae is to keep it dry or water it sparingly. Beetle eggs will die without sufficient moisture, so limiting water can help eliminate eggs before they hatch into larvae.
- Many beetles lay eggs in July, making it crucial to keep the lawn dry during July and August.
- Beetles will avoid laying eggs on dry lawns, so consider withholding water during the last week of June as well.
Treat larvae with synthetic pesticides
Determine if synthetic pesticides are necessary. Synthetic pesticides can be potent and hazardous to use, as well as harmful to the environment. To ensure their use is justified, first confirm the presence of larvae and assess whether the problem is severe enough to warrant pesticide application.
- Look for signs of larvae, such as holes in the lawn, patches of grass with missing roots, brown spots, and spongy soil.
- To confirm larvae presence, dig a 30 cm x 30 cm area about 5 cm deep and search for grubs.
- No treatment is needed if you find fewer than 5 larvae, and avoid treatment if the lawn is healthy with fewer than 10 larvae. Treat the lawn if you find 10 or more larvae.
Consider using synthetic pesticides to eliminate all types of larvae. After thorough inspection and confirmation of larvae presence, you can use pesticides that kill larvae almost instantly. Two effective options are carbaryl and trichlorfon (sold under the brand name Dylox).
- Water the lawn both before and after applying the pesticide to ensure the chemicals penetrate the soil where larvae reside.
- Apply treatment pesticides during fall, spring, and before May.
- These pesticides are available at home improvement stores.
- Always wear gloves, a protective mask, and other safety gear when applying pesticides.
Apply preventive pesticides for the next year. This is another type of pesticide that helps control larvae and eliminates subsequent generations of larvae. Typically, this pesticide is used in June or July, after the application of treatment pesticides.
- Make an effort to protect pollinating insects (such as bees) from pesticides. Mow the grass to remove flowering weeds before applying pesticides.
- To prevent grass from burning, ensure thorough watering throughout the summer after pesticide application.
- Preventive pesticides are sold under the brand names Merit and Mach 2.
Advice
- Plant additional herbs and greenery in your garden, such as rosemary, mint, garlic, marigolds, and boxwood, as they can deter the growth of insects like beetle larvae.
- Nasturtiums can attract bees and beetles. If you wish to grow this plant, place it around the garden edges to prevent insects from attacking other plants.
Warning
- When applying pesticides, ensure you use all protective equipment as recommended by the manufacturer, which may include long pants, long-sleeved shirts, gloves, safety goggles, boots, and a protective mask.
- Always read the instructions and warnings on the product label carefully before using pesticides. Follow the recommended dosage and handle with care.
- Wash your hands, face, and clothing immediately after using pesticides. Do not eat, drink, or smoke while using pesticides or until you have thoroughly cleaned yourself.
