Milky Spore Grub Control For Japanese Beetles

Looking for grub control?  Here’s an alternative to grub control using a bacteria called Milky Spore. Instead of Scotts Grub Ex or Bayer Advanced Grub control products, try an organic solution. There’s no way to tell when they invade your lawn, because they are underground where you can’t see them.

What is Milky Spore?

Milky Spore is a naturally occurring bacterium that affects only Japanese Beetle.

How fast does it work and how long does it last?

Milky Spore begins working as soon as it is applied as long as grubs are feeding. Once grubs are infected they will multiply the Spore by several billion times and spread it further. In warm climates good control can occur in one to three years. Once established in a lawn, Milky Spore has been known to last 10 to 20 years.

Milky Spore Powder by Saint Gabriel is a naturally occurring microscopic bacteria that kills Japanese beetle grubs before they can grow into  adult beetles. It is a long term solution because it survives winter temperatures. The milky spore population increases each year, reaching peak effectiveness about three years after application. You can use milky spore on lawns and in the garden.

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Can I use Milky Spore in the vegetable garden?

Milky Spore is harmless to food crops. It is organic. Milky spore is not a chemical pesticide and it may be used in gardens.

Can I cut my grass after applying the Spore?

DO NOT mow your lawn immediately after application. Wait until milky spore has been watered into the soil by rain or use a garden hose for 10-15 minutes.

How Do You Know If You Have Grubs?

Grubs feed on the roots of your grass which can become brown and die. Simply lift the dead grass and look for white larvae curled into the shape of a “C” about the size of a penny. Active grubs can completely destroy a lawn. As an alternative to chemical insecticides, most Lowes stores now carry Milky Spore for safe, long-lasting control.

Milky Spore targets and effectively works to attack and kill the white grubs of Japanese Beetles.  Milky Spore can be applied anytime the ground isn’t frozen. It comes in powder form that’s typically applied just once or twice, and in granular form, which is to be applied both spring and fall for two to three years. Once in the ground, milky spore is reasonably effective against Japanese beetle grubs for 10 to 15 years.

Milky Spore Grub Control-How it works.

At the immature beetle stage, the Japanese Beetle grub feeds on the roots of grass and other shallow-rooted vegetation. The adult beetle feeds on fruits, flowers, shrubs, garden plants and the foliage of some field crops.

Japanese beetle grubs live underground and typically feed on the roots of lawns.  As the Japanese Beetle Grubs eat the roots of your lawn and landscape plants, they eventually kill them.  Once they mature into flying beetles they can devour the leaves of the plants too and then re-infest the ground with their eggs.

After you apply milky spore powder, it becomes one of the things they ingest. The bacteria that comprise milky spore grow inside the grubs and rapidly multiply. This causes a disease that results in their eventual death. Grubs that become infected can live for several months, especially over winter. But in spring, when spores appear in their blood, they stop growing and die.

The adult Japanese beetles pupate in the late June to mid-summer time frame in the northeast to central United States.  The beetles feed on flowers and leaves of shrubs and garden plants. During this adult stage the beetles also mate and the females lay eggs in the soil in late July – early August.

The eggs hatch soon afterwards and in this larval or grub stage, they feed on the roots of grass and other plants. As the weather gets cooler and winter approaches the grubs go deeper in the soil and feeding declines as they winter. This is the best time to apply grub control.  Prior to when adult beetles lay eggs in your lawn.

When To Apply Milky Spore

A common misconception is that grubs can be controlled just like any other insect. That won’t work with grubs. Grubs become infected by swallowing a spore. They do not become infected by coming in contact with any product. They must ingest the product. Since grubs feed less in the spring, the effect is not as great as in late summer or fall.

Although Milky Spore can be applied any time the ground is not frozen, a summer to early fall time-frame, when the grubs are close to the surface and actively feeding makes grubs extremely vulnerable to infestation. This is also the optimal time frame for yearly applications of Milky Spore to increase bacteria in the soil.  There are guidelines on the package that should be followed for best results in your area.

Milky Spore begins working as soon as it is applied as long as grubs are feeding. Once grubs are infected they will multiply the spore by several billion times and spread it further. In warm climates good control can occur in one to three years. In colder areas like Ohio, Michigan  and New England, it takes about three to five years.

Once established in a lawn, it has been known to last 10 to 20 years.  Spores in the soil are swallowed by grubs during their normal pattern of feeding on roots. This ingestion of the spore activates reproduction of the bacteria inside the grub. Within 7–21 days the grub will eventually die and as the grub decomposes, billions of new spores are released into the soil.

Milky spore can be applied spring, summer and fall. However, it should be started with the summer application in late July to August. This is the best time to apply the treatment, as the grubs are close to the surface of the warm soil, feeding on roots. Some recommend to get lasting control, you should apply 3 times a year for 2 years.

How To Apply Milky Spore Video

Milky Spore is available in two sizes at Lowes:  St. Gabriel Organics 20-lb Bag Milky Spore Powder: Item #: 153171 and 10-oz Milky Spore Grub Control: Item #: 79145.

It is less harmful to the environment than chemical insecticides, however, if you need immediate results for your grub problem you may have to try a chemical alternative. To be more effective, after treating with milky spore, you can continue to use other treatments to eliminate adult beetles, such as Scotts Grub Ex  or Bayer Advanced Grub Control.

Life cycle of the Japanese beetle

The adult beetles normally emerge during the last week of June through July. They begin to release an pheromone that attracts additional adults. Newly emerged females also release a sex pheromone that attracts males. After feeding and mating for a day or two, the females burrow into the soil to lay eggs at a depth of 2 to 4 inches.

In early spring grubs awaken from hibernation and begin to work their way up in the soil to just below the grass. In late May and June, grubs change into a pupae stage before turning into beetles. These beetles later feed on flowers, trees and shrubs.

In the summer, beetles burrow into the lawn and lay eggs that will hatch into new grubs.  In late summer and early fall, newly hatched grubs feed on your grass roots before digging deep to hibernate for winter. It is during this time that grubs do the most lawn damage as they feed prior to hibernation.

Females lay 1 to 5 eggs before returning to plants to feed and mate. This cycle of feeding, mating and egg laying continues until the female has laid 40 to 60 eggs. Most of the eggs are laid by mid-August.  The eggs hatch in 8 to 14 days and the first larvae dig to the soil surface to feed on roots and organic material.

Grub Control Treatment and Damage

Grub eggs take 18 to 45 days to mature.  Most of the grubs by late September and October dig deep into the soil to overwinter. The grubs return to the surface in the spring as the soil temperature warms, usually in mid-April.

Tip:  You have two main options for grub control.  Chemical or bacterial approach.  The Scotts and Bayer grub control products are for active infestations of grubs and you can see results in 24 hours.  They are very effective against Japanese Beetle grubs as they hatch from the egg in mid-to late- summer but are not very effective against grubs at any other stage and should not be used.

Milky spore is for long-term control. Unfortunately, milky spore doesn’t make much of an immediate impact. It takes a few years to build up to its maximum protection.

Milky Spore is available at Lowes , Home Depot, Ace Hardware and online at Amazon.

By Victoria Stone