15 Interesting Facts About Grubs | How to Tell If You Have Grubs?

Have you ever noticed brown patches in your yard that have never turned green? This may happen due to the presence of Grubs in your yard and their feeding! Lawn Grub is basically a larva that eventually turns into an adult creature.

These Lawn Grubs are also known as White Grubs that are primarily in the immature or larval stage of Scarab Beetles like that of Japanese Beetles, June ‘Bugs’ (Beetles), or the European Chafers. These Grubs are known to curl into a ‘C shape’ when they are disturbed.

White Grubs are considered serious pests in many areas of the world including Africa and India. They feed on grass and plant roots, thereby destroying the plant and the entire yard as a whole!

In different parts of the United States and in the rest of the world, these Grubs are known to attack plant roots and largely destroy yards.

Although you may consider Grubs as an eternal enemy of your garden, it would be quite interesting to note some of the fascinating facts about them.

Let’s explore some of the most important and interesting facts concerning the distinctive characteristics of Grubs!

15 Interesting Facts About Grubs

This article intends to present the 15 interesting facts relating to Grubs, their lives, livelihood, lifespan, habitation, predators, feeding habits, activities, distinctive peculiarities and characteristic features, behaviors and more.

1. What Are Grubs? What Is a Grub’s Habitat?

In simple language, White Grubs are basically the larval stage of different Scarab Beetles, such as May and June Beetles, Japanese Beetles, or European Chafers.

These are generally white or creamy colored Beetle larvae that have dark brown heads and three apparent pairs of legs. These creatures can damage a lawn by feeding on dead organic matter and the roots of plants and grasses. They usually curl into a ‘C shape’ when disturbed.

White Grubs are considered pests nearly all across the world. Their habitat mainly consists of the topsoil since Grubs are primarily found just below the surface of the yard or garden.

According to the University of Minnesota Extension, more than 200 Phyllophaga species of White Grubs are native to various parts of the United States and Canada, amongst all of them only a few species are known to be crop pests.

2. What Causes Grubs?

Soil conditions are probably the most important factor contributing to the damages incurred by Grubs since the condition of the soil greatly affects the Grub population and the severity of the damage they cause.

Infertile soil that lacks organic matter attracts larger Grub populations since their natural enemies like ground spiders and ants require organic matter to sustain.

Compacted soil also results in greater Grub damage since the grass root in such soil cannot grow more than 2-3 inches and Grubs are likely to feed on them.

Other factors, such as the number of pesticides or insecticides sprayed in the yard and regular inspection of the yard by various kinds of birds, also affect the causes of Grubs.

The more natural enemies of Grubs are killed due to the spraying of insecticides, the more is the growth of the Grub population.

Lastly, if a yard is regularly inspected by different kinds of birds that feed on Grubs, their number definitely decreases. However, if that’s not the case, the yard automatically attracts Grubs.

3. How Long Do Grubs Live?

All the White Grub species complete their life cycle within a year, except a few like the June Beetle species that generally have a life cycle of 3 years.

The White Grub life cycle consists of four stages; Egg, Larvae, Pupa, and Adult. Depending on their species, the eggs are generally laid between June and August.

Under favorable conditions, these eggs hatch within 2 weeks. In its larval stage, the Grubs extensively feed on grassroots and spend the winters deep inside the soil.

When the spring arrives, the larvae once again come up and start feeding on grassroots and destroying the yards.

Once they finish their feeding, they transform into Pupa and ultimately into an adult which comes out of the soil and after a few weeks again lays eggs to start the next cycle.

4. What Do Grubs Turn Into?

White Grubs usually turn into some kind of Scarab Beetles, such as Japanese Beetles, Asiatic Garden Beetles, June Bugs, European Chafers, Oriental Beetles, etc.

These Grub species are mostly found in the United States. These adult Beetles come out of the soil after a few weeks and lay a fresh set of eggs for the next cycle.

5. What Do Grubs Eat?

White Grubs generally feed on plants and grassroots. However, the dietary preferences of Grubs predominantly depend on their diverse species.

The species of Grubs that live primarily on the surface of the soil, are mostly known to consume grass leaves.

However, most of the Grub species that dwell inside the soil, survive by consuming a wide range of plant roots including turf grass, fruits, and vegetables. They are also known to feed on young seedlings and dead or organic matter that are found in the soil.

6. What Eats Grubs?

Like any other insect species, Grubs are a very important source of protein and calories. Grubs are therefore a highly fed food supplement for many animal species.

Some of the predators of Grubs include Skunks, Raccoons, Moles, Armadillos, and different kinds of Birds.

Raccoons and Skunks usually pull up grass and/or roll it back in order to get and feed on Grubs.

Moles also feed on Grubs and Earthworms that are usually present in the soil.

Different species of birds can easily find and hunt down Grubs from the very top of the sky. These birds usually pick out the Grubs from the soil without causing any serious damage to the lawn.

7. Where Do Grubs Come From?

The life of Grubs starts when an adult Beetle lays eggs during the springtime. The Grubs come out of the eggs when they hatch which usually takes around 2 weeks under regular favorable conditions.

Grubs generally evolve in three stages, i.e Larvae, Pupa, and Adult.

Thus, if you are wondering from where these ugly-looking worms came into your lawn, the answer is simply that Grubs are the larval stage of Beetle species that come out from soil when they are hatched out from their eggs that have been laid by adult Beetles of the previous season.

8. How To Tell If You Have Grubs?

As we have already noted, Grubs tend to feed on plant roots and therefore destroy your yard from the very grass-root level. So, how to determine Grub infestations in your yard? There are few signs to tell if you have Grubs in your garden or lawn.

  • If you find Moths or Beetles flying around the grass level, then your yard may already have or might indicate an imminent one since these are the adult form of Grubs and may have already or might in future lay eggs in the same yard.
  • If you find increased animal activities, such as that of hanging out or feeding in your yard, also indicates Grub presence since animals like Birds, Raccoons, Skunks or Armadillos feed on Grub and therefore might be spending time in your yard in order to feed on these Grubs.
  • Another most important sign of Grub infestation is the presence of brown patches in your yard. Grasses turn brown when their roots are being attacked by Grubs. Thus, keep investigating for these visible brown patches since their presence indicates that the yard has a Grub presence.
  • Some other signs of Grub presence are the feeling of bouncy or loose grass underfoot or having severely damaged grasses in your lawn. All these indicate that your yard might be having a Grub infestation.

9. When Do Grubs Hatch?

The eggs laid by the adult Beetles usually hatch in the period between the months of August and October. It usually takes these eggs 10 to 14 days to hatch into 0.1-inch Grubs.

However, there are certain factors that affect this exact hatching time frame, such as soil moisture and temperature. In a regular favorable condition these Beetle eggs hatch in about 2 weeks.

10. What Damage Does Grubs Cause?

One or two Grubs in a yard generally don’t cause any severe damage to that yard. However, if that number increases to as many as 100 or more Grubs per square yard, then it can definitely cause tremendous damage to the yard.

Grub infestations in a yard can totally ruin that yard and generally lead to the formation of patches of thinning turf that increase over time. Grubs also hamper the growth of new and healthy plants in the yard since they feed on plant roots.

What Do Grubs Do to Grass?

The primary destruction that Grubs do is destroying the grasses of a yard.

Since these worms feed on the roots of plants and grasses, their feeding process leads to the total destruction of grasses.

This causes the formation of brown patches in the lawn and the death of certain sections of grasses.

11. What are Grubs Good For?

Grubs may not be good for your garden or lawn, but that doesn’t necessarily mean that they are totally worthless. These Grubs are generally known to play a very crucial role in the environmental processes.

Not every Grub species is bad for yards since not all the species of Grubs consume plant roots. Certain species of Grubs are also known to feed on decaying and organic matter found in the soil.

This certainly increases soil fertility to a greater extent. Also, these worms are very likely to be eaten by creatures such as Birds and animals. Grubs are therefore the primary food supplement to many creatures.

12. When Are Grubs Most Active?

The high time of Grub activity normally starts in the late summertime and continues till the late fall. Their activities again rise for a brief period of time in the early spring.

While the adults are most active during the springtime, predominantly between March and May and once again in the midsummer days, the Grubs on the other hand are mostly active from May to June and again from August to September.

They become mostly inactive during the Winters and penetrate deep inside the soil.

13. What Temperature Are Grubs Active?

When the soil temperature reaches a minimum of 50 degrees Fahrenheit, White Grubs tend to move upwards and start feeding on grassroots.

During the colder months of October and November, when the temperature drops significantly, Grubs generally tend to withdraw themselves from the uppermost soil layers and penetrate deep inside the soil in order to spend the winter months.

As the soil temperature rises again, during the next springtime, these White Grubs return to their previous location and resume their feeding.

Once mature enough, they once again penetrate deep inside the soil and enter the next Pupal stage ultimately evolving into Beetles within the next few months.

14. Difference Between Fungicide and Grubs

Both Fungus and Grubs are generally known to cause similar-looking damages to your yard, that is the formation of brownish, yellowish, or deadly and sick-looking patches in the yard.

Now, how to identify which damage is incurred by Grubs and which one is caused by Fungus? In order to conclude the answer to this question, you have to perform a simple task.

Simply reach out to the discolored area of your yard and try to pull out the sick-looking grasses. If the grasses come out easily that means their roots are no longer attached to the soil since they have been destroyed by Grubs.

On the other hand, trying a different method, if you step on the grasses and they don’t pop back up, in that case, this is most certainly caused by Fungus which has made the grasses sick but hasn’t attacked the root of the grass.

Therefore, Fungus makes the grasses deadly and sick while Grubs feed on the roots and kill them. It is therefore important to check their presence in yards regularly and eliminate them when necessary.

While Fungicides are used to eliminate this Fungus from yards, several chemical and biological ingredients are used to exterminate Grubs from lawns and gardens.

15. Types Of Grubs and How to Identify Them?

There are a number of Grub species that are scattered worldwide. All these Grub species share more similarities than differences and it may seem quite hard to identify them with your naked eyes!

Their similarities range from physical appearances, feeding habits to active seasons. However, there are slight changes in the behaviors of these different Grub species. A few common Grub species that are generally found in the United States are discussed below.

1. European Chafers

The adults have an oval and medium-sized body that is reddish-brown in color. They have darker heads and look similar to June Beetles that grow to ½ an inch. They live for about one year and the females lay around 20 to 30 eggs in a month.

2. Oriental Beetles

These species are native to Japan and were first discovered on American soil during the first part of the 20th century. They generally emerge in late June and their activities increase greatly during the month of July. Their life cycle is almost the same as the European Chafers and the eggs take around 14 days to hatch.

3. Japanese Beetles

These Grub species are also native to Japan that were later found in the United States. The adults of these species are 7/16 inch in length and have a metallic green hue in their oval bodies with copper-colored wings. They also share a similar life cycle with the European Chafers species.

4. Asiatic Garden Beetles

Adult Asiatic Garden Beetleshave a brownish-red hue and are normally around ⅜ in length. The female beetles typically lay 40 or more eggs after mating. The Grubs then hatch after 2 weeks and they start feeding on grassroots.

Some of the other major Grub species are Northern and Southern Masked Chafer, May or June Beetles that have a three-year life cycle, Green June Beetles, and Black Turfgrass Ataenius that usually has a two-year life cycle.

Although it may seem quite difficult to identify the different species of Grubs since they all share features including physical appearances, experts have unique techniques to help them identify different Grub species.

Grubs are generally identified by observing and noting the shape of their anal slit, meaning the anal opening of the Grub, and the raster pattern, which indicates the hair and spine pattern that is present in front of the anal slit.

For instance, Asiatic Garden Beetles are known to have a “strongly Y-shaped” anal slit and “crescent-shaped” rows of spines, but European Chafers usually have a simple “Y-shaped” anal slit and “diverging rows of spines”.

Also, while May/June Beetles have “Y-shaped” anal slits and “parallel rows” of spines that are also known as “closed zipper”, Oriental Beetles generally have a “crescent-shaped” anal slit and two distinctive rows of spines.

Thus, we can identify specific Grub species by looking forward to these two main backend characteristics of Grubs. Different Grub species have different anal slit and raster patterns.

Final Words:

Thus in order to conclude, we can definitely say that Grubs are creatures that are the least favorite of gardeners, but at the very same time, they also have some of their own unique peculiarities. We have explored their lives, livelihood, lifespan, food habits, chief characteristics, and behaviors.

Although Grubs feed on grassroots and totally destroy the yards, they are also known to help in other crucial environmental roles.

They are themselves food items of many creatures and some species of Grubs actually help in regenerating the soil. All the Grub species share common features, however, some distinctive characteristics of them can help us to identify their different species.