How to Prevent or Treat Lawn Grubs in the Fall

Lawn Grubs are the larval stage of June beetles, European chafers, or Japanese beetles. The eggs hatch 10 days after being laid by the female beetles. Lawn grubs possess a creamy white body, a reddish-brown head, and three pairs of legs on their thorax. These lawn pests are one inch long and can be found in the top few inches of the soil in a C-shape.

They feed on organic matter, including grassroots. This consistent feeding causes the grass to develop irregularly shaped yellow or brown patches, indicating the death of grass in those areas. After feeding during the fall months, grubs burrow deep into the soil where they overwinter. Once spring returns, they resurface or burrow upwards, where they resume feeding until late May and then transform into pupae.

Adult Japanese beetles emerge around the first week of July while European chafers emerge about two weeks earlier. However, before insecticide application do a thorough inspection to ensure it is grub.

Signs that your Lawn May have a Grub Issue

Besides your grass developing yellow or brown patches, there are other signs to keep watch for. Patches of grass that are dead take on a spongy feeling because of the grassroots being eaten. The grass is easily pulled up if little pressure is applied. If skunks, raccoons, or birds have taken a sudden interest in your lawn by digging ( grubs are a food source) is a sign that grubs may be just beneath the soil surface.

A simple test that can be done to see if grubs are present is to fill a bucket with soapy water and pour it over damaged or suspected areas. Wait for at least 10 mintues or a bit longer. If grubs are there they will come up to the surface. This test is most effective when done at dawn or dusk when grubs may be most active.

Preventive Measures

Becoming proactive by taking the necessary steps before a grub issue arises will help to maintain a healthy lawn and the application of insecticides that contain imidacloprid and chlorantraniliprole during (April to mid-July) late spring and early summer before grubs hatch will offer much help. For this method to work timing plays a major part. This should be done right before adult beetles lay new eggs. However, if grubs are already present and actively feeding this approach will not be effective.

Grub Control Curative Measures

If on inspection you discover you have a grub issue where they are actively feeding ( from late July through August)  an insecticide label for grub will bring control. This time of the year when the grub population is high they are more susceptible to treatment. Granular products that are labeled for grub control with the help of a fertilizer spreader will help distribute the product evenly over the lawn surface.

Neem oil will not kill grubs directly but will disrupt their ability to feed, grow, and molt which will eventually eliminate them. Neem oil will also control other pests. Allowing birds on your lawn can help in the control of grubs as long as the infestation is not out of control other wise it’s best to use insecticides. A natural option is to use nematodes, nematodes are tiny parasitic worms that will kill grubs.

This works by shaking up nematodes in water followed by applying it to your lawn, be aware that this method is slow-acting and long-term taking up to 3 years to bring complete control of the infestation.

 Bacillus thuringiensis (Bt) is a much faster way to provide quick results, this product will kill a wide variety of grubs and will protect your lawn from grubs year round.  When applying insecticides Don’t allow kids and pets in the treated area until it has completely dry.

Note: Natural methods will take a much longer time to control grubs and you’ll risk more lawn damage the more time it takes.

Repairing Grub Damage

Re-seeding and fertilizing your lawn during the fall months will repair damaged grass and discourage beetles from laying new eggs.

What Attracts Grubs

• Lawns that have poor drainage or overwatering your lawn will not only encourage grubs but other pests including grass root rot.
• When treating lawns for grub infestation avoid excessive watering since grubs thrive under moist conditions.
• Since a build-up of thatch will encourage  the presence of beetles to hide and lay their eggs it’s best to discourage thatch build-up by removing thatch manually with a thatch rake or mechanically with a machine-powered dethatcher
• Aerating your soil when needed will help with proper water drainage that will reduce moisture buildup which will discourage grubs.

Additional information

• Good cultural practice is a great way to grow and maintain a healthy lawn, the proper location of installation, the right soil type, the right amount of water and fertilizer, and the proper mowing height will encourage a lawn to thrive so even when pests show up your lawn will bounce back quickly once the proper treatment is put in place.
• Before Pesticide application make sure to identify the insect or pest problem correctly.
• Make sure you’re wearing your protective gear before pesticide application because safety comes first.
• Before insecticide application read and follow the manufacturer’s label for safety and best use.

Conclusion

The presence of grubs can destroy a lawn by their consistent feeding especially when they are active, but with the proper timing providing a preventive insecticide or the proper application of insecticides if they are already present will bring complete control. Calling a professional lawn care service to do the job for you if you’re not up for the challenge will also help to bring your lawn grub problem under control.