Grubs: The Silent Destroyer Lurking in the Garden

By Ron Harrison, Ph.D., Entomologist and Orkin Technical Services Director

Green grass, blooming flowers and sprouting vegetables – there’s no sight more beautiful to a gardener. But the beauty can be easily destroyed, and bringing a garden back to life can be frustrating and challenging, especially if you don’t know the cause of destruction. A number of factors – including animals, disease, and environmental conditions – can contribute to damage in the garden. If you ever see brown patches that never manage to turn green, grubs may be lurking in your soil. Grubs can cause serious damage to lawns and gardens, so it is important to eradicate them before they become a problem. Knowing how to detect these pests is the key to managing them.

How to Detect Grub Worms

Grubs are the larvae stage of beetles, such as Japanese beetles, June beetles and chafers, which cause damage to the garden. They are often white or light-colored, C-shaped creatures. Grubs can reach up to one inch in length once they reach the pupal phase, which is a resting phase before adulthood. Grubs feed on the roots of grass and other plants. Some indications of grubs feeding on lawn and gardens include:

• Brown patches
• Irregularly shaped dead patches
• Turf that has become spongy

The majority of grubs appear mid-summer in sunny areas. To find grubs, look and listen. Keep an eye out for patches of grass that never turn green, lift them and investigate. If the dead patch rolls up or, when lifted, reveals that the grass has no roots, grubs are likely to blame. Some species of grubs feed on dead wood – outdoors or even inside a home – and can sometimes be heard making a clicking noise when feeding.

Grubs are difficult to spot, so keeping a close eye on the overall health of your plants is important. If plant aren’t growing like they should be or appear to still need water after watering, it could mean grubs are eating the roots or stealing the plant’s nutrients.

Strategies for Preventing Grub Infestations

The best time to treat grubs is in late summer or early fall because they are still fairly small and close to the surface. In the spring, grubs may be less susceptible to treatment because they are often in the pupal phase when they do not feed as often. Because of this, insecticides are less effective.

There are several natural options to treat grubs, including nematodes, milky spore and neem oil.

• Nematodes: Nematodes are microscopic worms that either penetrate through the grub or are ingested. They release bacteria that typically eliminates the grub within 48 hours.
• Milky Spore: Milky spore is a fungus in a powder form that can be spread on lawns to reduce grub populations.
• Neem Oil: Neem oil is compound that comes from plants and can reduce insect feeding and mating to prevent larvae from maturing. It can also help fight plant-damaging fungi, mildews and rusts.

If grubs continue to damage your lawn or garden, contact your local agricultural extension office or garden supply store for advice or resources.

Atlanta-based Orkin is an industry leader in essential pest control services and protection against termite damage, rodents and insects. The company collaborates with the Centers for Disease Control and Prevention (CDC) and eight major universities to conduct research and help educate consumers and businesses on pest-related health threats. Learn more about Orkin at http://orkin.com.

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