Insect problems galore

Asked September 16, 2016, 9:08 AM EDT

I am the stadium keeper at a high school. Our football game field is a sand based Kentucky blue field. I have what was determined last year as European chafer. With some miscommunication last years attempt to control these insects failed miserably. Aug 31 I noticed browning, checked and I had 43 grubs in an 18" square section. I applied carbaryl at 8 pounds per thousand. On September 12 I applied another application, same dosage. Last night after our football games, which really tore up the field, I pulled back some of the sod and noticed there had to be just as many. They are a dark color, I believe they are effected by treatments (some anyway). Is there any thing I can do to help in this situation, or do I just plan for next year? Any response would be greatly appreciated.

Berrien County Michigan lawns and turf

1 Response

Here's is an article about white grubs that you might find useful. The dark colored grub you saw after treating with Sevin are most likely dead of dying. Consider using Merit (imidacloprid) next July.

By Terry Davis, MSU Department of Entomology

Lawns are rapidly greening and a number of people in the mid-Michigan area have noticed patches of lawns that are appearing to be dead. After digging around the edges of the dead patches, 3/4 inch-long, white, c-shaped grubs will often be found. If you find more than five per square foot, it may be time to consider using an insecticide. If you are planning to reseed, apply an insecticide first because grubs can eat grass seed. The grubs in home lawns are usually European chafer, Japanese beetle or a mix of both. The grubs will continue to feed through early May, at which time they pupate. Adults emerge in mid-June (European chafer) and July (Japanese beetle). The new larvae are large enough to see by Labor Day. They feed on turf roots from August to early November. Dry conditions in April or in October will make damaged areas of lawns more pronounced.

So – if you have decided to try an over-the-counter grub control product, you will find a dizzying variety of products currently in stores. Since spring is the big season for selling lawn care products, there are several things on the shelf that should be used later in the season for control. Unfortunately, there are a number of products listed for grub control that will not work.

On a trip to three of the local stores with garden sections, I found a number of products touted as “Grub Killers.” I also noticed a considerable amount of overlap between brands and active ingredients. Since curative grub products, preventive grub products and snake oil were all in the same areas of these stores, I suspect a large number of homeowners have bought and applied things that will not do what they thought they would. The assumption that any product claiming to kill grubs will really work – is wrong. The first critical issue is to determine what active ingredient the product contains by looking at the label. Look beyond the product name and find the small print on the bottom corner of the bag that indicates the name of the active ingredient.

Do not use products containing lambda-cyhalothrin, bifenthrin and permethrin for grub control. Products containing these ingredients will not work for subsurface insect control when applied to the soil surface because they bind tightly to organic material and do not move down to where the grubs are feeding. These products work well for turf feeding insects that live on the grass leaves or soil surface but not for insects that feed on the roots. I found one product called ‘Triazicide’ (containing lambda-cyhalothrin) that claimed to be good for grub control. It is unlikely that it will do anything for grub control. I also located two products containing permethrin that listed surface insects but not soil-dwelling ones. Permethrin, lambda-cyhalothrin and bifenthrin will work well for aboveground insects but not for grubs.

Products containing imidacloprid or halfenozide will not give good grub control during the spring and fall months. They are preventive products and do not work well for large grubs. Although the bag says apply anytime from May to August 15, it is highly recommended that these products be applied and irrigated into the soil during the first two weeks of July. If applied now, they will have little effect on the grubs currently in the lawn and furthermore, they will degrade by the end of July when the chemical works well for killing the newly hatched grubs. I specifically saw ‘Grub-Ex,’ ‘Bayer Advanced Season Long Grub Control’ and ‘Spectrum Grub Stop’ that contained one of these active ingredients currently in stores.

Any products that contain carbaryl (Sevin) or trichlorfon (Dylox) will work well during the spring, late summer and fall. They can be applied in the spring (from March to mid-May) or in the fall (August 1 to November 1). These are considered curative compounds as opposed to the preventive compounds mentioned above and will kill the grubs currently in the ground. It is necessary to irrigate after applying any curative product to get the chemical to the grubs. Run a lawn sprinkler for at least 60 minutes over treated areas (fill a bucket to a height of 1/2 inch). It will take 10 to 14 days for the grubs to begin to die. One trichlorfon product called ‘Bayer Advanced 24 Hour Grub Control’ states that it will kill grubs in 24 hours. However, I doubt that any of the insecticides will kill grubs in the soil in much less than five. Do not apply any curative compound after May 15 as the grubs stop feeding in late May.

I also noticed a product called ‘Milky Spore Disease’ from St. Gabriel Laboratories that is listed as a safe control for Japanese beetle. It is to be applied three times a year for two years before an effect is to be noticed. This product contains bacteria that cause a natural disease of Japanese beetle grubs. It will not work well on European chafer. Use this product to inoculate your lawn with milky disease, but do not expect it to work like a pesticide. It will infect a small proportion of grubs in most years, helping to keep them under control. Only use Milky Spore disease for two years to inoculate your lawn, it will persist by itself for the next 20 years all by itself. It is not guaranteed to prevent grub damage to lawns.

In summary

Check the bag to determine what active ingredient the product contains.

Do not use products containing lambda-cyhalothin, bifenthrin or permethrin for any phase of grub control.

Do not use preventive compounds such as halfenozide or imidacloprid in the spring and fall. Use them during the first two weeks of July to control grubs for fall.

To kill grubs currently in the yard – use carbaryl or trichlorfon and irrigate.

Treat all pesticides with respect. Wear rubber gloves, rubber boots and long pants when handling or applying insecticides to your yard. Do not allow children or pets on a treated lawn until after the chemical has been thoroughly watered-in and has had a chance to dry.