What Are Grubs And Where Do They Come From? Signs To Look Out For

Ritwik Bhuyan
Mar 04, 2023 By Ritwik Bhuyan
Originally Published on Oct 14, 2021
Edited by Jade Scott
Fact-checked by Sakshi Raturi
Close up of white grubs burrowing into the soil.

Certain beetle species have immature or larval forms which are known as grubs.

You must have noticed white-colored, C-shaped creatures turn up while digging the ground of your yard. These white grubs are actually the larvae of Japanese beetles, June beetles, or European chafers, feeding on the roots of the grass in your yard.

These wrinkly creatures, called grubs, can be nearly one inch in length and have very soft bodies with legs near the head. You won't even notice these small worms in natural circumstances.

Their presence is only known when significant damage has already been done to your lawns. A grub infestation can be observed on the ground as they live in the soil and feed on the tender roots of the grass in the lawn.

We know beetles are known to develop in four different stages.

The life cycle starts with the female adult beetles laying eggs in the soil of the lawn in July (mid to late summer). The grubs appear two weeks later as the eggs hatch and turn into larvae.

The grubs in your lawn will feed, molt, and grow in this period. When the temperatures fall in the autumn season, the lawn grub burrows beneath the soil and spends the winter.

Grubs come back to the surface in early spring. As they keep on feeding on the roots of the grass, grubs then reach the third stage of the life cycle which is the pupal stage.

The adult beetles then emerge from the pupae in late June or early July and start searching for food and another to mate with. This cycle of grubs repeats itself and your grub infestation will increase tenfold if not dealt with.

You can spot a grub problem in your garden or lawn in the form of irregularly shaped brown patches. Grub problems tend to arise mainly in August (late summer).

The lawn turf infested with grubs will easily peel off from the surface as the roots of the grass are already damaged. You can also notice birds moving near the brown patches of the turf looking for these grubs to kill and eat.

Skunks, birds, and moles love feeding on grubs and you would think this would help your garden or lawn.

But no, these animals will further damage the lawn without care as they go on searching for the lawn grubs in the soil. Adding nematodes can help, but will discuss that in more detail later.

To prevent these different species of grubs and beetles from damaging your lawns, you should know how to keep the lawns and garden healthy. Keeping the turf two inches high can help as beetles lay eggs in short grass.

Also, remember to fertilize the lawns often.

Water the lawn and garden regularly to help the grass grow more quickly and with stronger roots.

As grubs lay eggs in the soil, they prefer doing it in undisturbed soil so make sure to aerate the lawn often. There are also chemical and natural treatments and lawn care products for grub infestation depending on the species of grub, so judge the turf of the lawn first before starting to treat for grub control.

If you enjoyed this article, why not also read the answers to the questions what are jiggers and what are mango worms here on Kidadl?

Where do grubs come from?

Grubs are the larval form of Japanese beetles, June beetles, or European chafers (as well as other beetle species) that can infest your lawn and destroy all the crops and flowers in it.

At first, you might notice two or three grubs in the soil of your garden and you might even find them gross. If you check back after a week or even a few days, you will notice the grubs have grown in numbers and have spread through the lawn.

Let's talk about where these grubs, that terrorize the grass turf of your lawn, come from.

White grubs or land grubs, as we know, are the larvae of some beetle species found in the world. These grubs are mostly found on a lawn near outer suburbs or areas near forests and parks.

Grubs are known to eat grass root networks and ruin the health of the lawn. For the best approach to lawn care, it is pretty important to have some kind of grub control in place to kill grubs.

Lawn grubs are not harmful when in small numbers, but once they grow, it is hard to control the worms.

When in small numbers, grub worms will even help the lawn by feeding on thatches on topsoil. This helps in lawn aeration and in turn, the overall lawn care.

What causes lawn grubs?

The most destructive lawn grub species are the larvae of chafer and Japanese beetles. The green June beetle, May and June beetles, the Asiatic garden beetle, and the oriental beetle are other species of grubs found in lawns all over the world.

There can be a number of reasons which might cause a large grub infestation within the soil of your lawn. A buildup of thatch in the turf can make grubs feed openly on your lawn and reproduce more.

There are, however, a lot of beneficial insects present in the soil of your lawn. Using chemical products on the lawn will kill these insects that are necessary for the control of the grub population.

This will increase the harmful insects like grubs on your lawn.

Chemical use can also affect grass growth. If there is less amount of grass, the lawn becomes stressed and pests find it easy to fall right into these situations.

Some species of beetles lay their eggs in this soil and in favorable conditions, the eggs hatch to produce more and more grubs in your lawn. Don't let it get out of control, otherwise, getting your lawn back in a good state won't be easy.

Grub Worms grow in soil.

How do you know if you have grubs?

Apart from the usual natural ways that grubs employ to infest your lawn, there are some other ways by which you can determine a grub infestation.

The easiest way to know if you have grubs in your yard is to look for dead patches of grass. These patches of grass in your yard will peel back like a carpet if you try.

The grub worms feed on the tender grass roots in the soil and totally damage the yard. The roots usually hold the turf in place.

Even before these patches are seen, you will notice that the turf feels spongy. Birds, armadillos, and raccoons will also dig up the garden in search of adult grubs to feed on.

All these signs are enough to determine if your lawn has grubs in it. It is very important to treat your lawn often with the right materials to stop this grub infestation from ruining your lawn.

Are grubs dangerous?

Yes, grubs can be very dangerous for your gardens as they can easily damage the whole area just for a feeding spree. Grubs are not toxic themselves, so do not worry if your dog accidentally eats a few of them.

Although grubs in small numbers can help the lawn in a few ways, the increase in the population of grubs that hatch in the soil can damage the whole lawn. To control the population, you can add natural predators of grubs like ants and ground beetles.

Even wasp larvae feed on grubs, so they can be added to the grass too. You can even try the natural commercial treatment of adding nematodes.

Nematodes are tiny worms that kill grubs.

Nematodes of the Steinernema and Heterorhabditis species are highly effective predators and can help restore the garden. Chemicals like trichlorfon, imidacloprid, halofenozide, or thiamethoxam can also be used to control the population of grubs.

Milky spore can be used too, but it is most effective against Japanese beetle grubs. Milky spore takes many years to show good results but it is a natural process and won't hurt your lawn with chemicals.

Milky spore is a bacteria used to control one species of beetles, however, the spring soil needs to be warm. To start to treat your lawn, firstly ensure that the grub is a larva of Japanese beetles.

It will take a few years to treat the soil with milky spore but once established, it will last almost 10 years. That's 10 years without grubs!

Nematodes, as we have briefly discussed already, are worms that work best in well-watered soil. You should purchase nematodes by looking at the species and the season.

They should not be exposed to direct sunlight, so it is better to apply them in the early morning or on overcast days. If you have a grub problem, apply them every two weeks. If you use nematodes as a precaution, use them two or three times a year.

What do grubs turn into?

The full life cycle of grubs takes a few weeks to complete.

It depends on species of beetles as Japanese beetles lay their eggs in late summer in July and August, while European chafers lay their eggs in late June. The eggs then hatch and the larvae (grub) start feeding on the grass roots within one or two weeks.

Grubs are known to feed until the fall season. They burrow deep into the ground to overwinter. After the end of fall and beginning of spring, the grubs burrow upwards to the grass roots.

They feed until May and then turn into pupae. Eventually, they will turn into adult beetles.

Here at Kidadl, we have carefully created lots of interesting family-friendly facts for everyone to enjoy! If you liked our suggestions for what are grubs then why not take a look at what are flies attracted to or why do fishes die when taken out of the water.

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Written by Ritwik Bhuyan

Bachelor of Arts specializing in English

Ritwik Bhuyan picture

Ritwik BhuyanBachelor of Arts specializing in English

A skilled content writer, Ritwik holds a Bachelor's degree in English from Delhi University. He has refined his writing abilities through his past experience at PenVelope and his current role at Kidadl. In addition to his proficiency in writing, Ritwik has pursued his passion for flying by achieving CPL training and becoming a licensed commercial pilot. This diverse skill set highlights his commitment to exploring multiple fields. Ritwik's experience in the aviation industry has provided him with a unique perspective and attention to detail, which he brings to his writing.

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Fact-checked by Sakshi Raturi

Postgraduate Diploma in Management

Sakshi Raturi picture

Sakshi RaturiPostgraduate Diploma in Management

Sakshi has experience in marketing strategy, social media planning, and recruiting industry experts for capstone projects, she has displayed a commitment to enhancing their skills and knowledge. She has won multiple awards, including a Certificate of Appreciation for Creative Writing and a Certificate of Merit for Immaculate Turut, and is always seeking new opportunities to grow and develop.

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