Tropical Sod Webworms – A Threat to Our Lawns?


Tropical sod webworms, known scientifically as Herpetogramma phaeopteralis Guenée, are pests that can cause the destruction of lawns in areas that fall under the tropical and subtropical zone. The southeastern parts of the United States, such as Florida, Texas, and countries in the Caribbean, fall into this zone. The impact of tropical sod webworms is very noticeable in these areas.

The impact of tropical sod webworms becomes very noticeable when their population is relatively high on a particular lawn. It is important to note that these webworms are not real worms but lawn caterpillars developing to become an adult insect.

They live in grasses and feed on them. The larvae stage needs to feed on grasses to get the nutrients they need to reach maturity. That is why the adult female tropical sod webworm lays its eggs on grass blades of turfs. Their damage can be minor, and sometimes it can be devastating as the grasses turn brown, dry, and then die.

Like most insects, the eggs of tropical sod webworms are usually laid by an adult female in the springtime. However, according to research, tropical sod can raise three generations within a calendar year. Tropical sod webworms can move from egg to adult in roughly ten weeks, making their lifespan pretty fast and short.

However, this does not mean they will leave your lawn after completing their life cycle because they will lay more eggs to raise another generation. This further increases the rate of infestation, and it can cause serious damage if left unchecked.

Because they thrive mainly in tropical regions, you won’t find them in regions with colder temperatures.

That is why you should find lasting solutions to their infestations, as it will go a long way rather than waiting for winter to help you get the job done. The reason for this is, after winter, these webworms will resume feeding on your lawn if left unchecked, and the insects will reproduce more of them.

What is Their Mode of Operation?

Tropical sod webworms mature into moths. The moths don’t feed on grass, meaning they pose no risk to your lawn. It is the larval stage of these insects that threatens the health of your lawn. Therefore, you should monitor the webworms before they reach maturity. The female moth can lay lots of eggs after mating. After these eggs hatch into larvae, they start feeding on grass. The grasses in the areas where they infest are usually lower than the surrounding grass in that area.

Tropical sod webworms feed on the edges of grass blades, and they can eat more into the grass, thereby removing the top layer of lawns. that is why the areas they infest are usually shorter.

As they grow, they eat more, as their population also increases, so does the extent of the damage they can cause on a lawn. This causes the sods to appear brown as if the lawn is suffering from a drought, and it can lead to the eventual death of the grasses in that area.

How to Differentiate Between Sod Webworm Infestation and Drought

Tropical sod webworms attack warm-season grasses. Warm-season grasses are types of grasses that thrive during the warm seasons; examples are St. Augustine grass, Bermuda grass, etc.

Therefore, these caterpillars’ activities are noticeable in hotter seasons, and given the kind of damage it causes, some people may think their lawn is affected by drought. The feeding pattern of tropical sod webworms causes grasses to get brown, dry, which further stunts their growth.

Dry brown grasses are also symptoms of drought, especially if there is no rainfall or water, and this is not strange in tropical seasons. So, you must verify the cause of these symptoms before taking action to solve them because treating the wrong issue, especially when it comes to tropical sod webworms, can only make things worse.

One thing to note when your lawn is affected by drought is that the entire lawn will have dry brown grass. The same cannot be said for tropical sod infestation as they tend to affect parts of your lawn before spreading to other areas.

Therefore, you should look out for sections of your lawn that look shorter and has dry and brown grasses. If you happen to find such sections, the chances are high that you may be dealing with tropical sod webworms infestation, and you have to take appropriate actions to stop their activities.

What are the Possible Solutions to Tropical Sod Infestation

Discovering these pests early is essential, and it also contributes to the success of treatments. Therefore, you have to regularly inspect your lawn and take action as soon as you spot cases of tropical sod webworm infestation.

The reason there is an emphasis on solving the issue as soon as it is noticed is that it will reduce the spread of the damage and prevent future infestation. To do this, you have to understand these insects’ lifecycle as it will be useful in stopping their spread and knowing the time to do that.

You can treat tropical sod infestations with different methods, which can be through chemical, cultural, or biological control methods.

You can use pesticides that are designed for such insects to remove them from your lawn. You have to apply these chemicals locally. That is, you have to apply it at the spot infested with sod webworms to get effective results. Spreading such pesticides throughout the lawn can kill organisms that are beneficial to the lawn and further damage the lawn.

Warm soapy water also irritates them and bring them to the surface. Sod webworms tend to do most of their feeding at night, while they hid under the grasses during the day. So, if you pour soapy water on your lawn, it will disturb them and bring them to the surface. Dish soap can help get the job done; however, it may not be very effective in killing them. So, you can gather the webworms and dispose of them or apply pesticides on them later.

They can also be tackled biologically by using fungi such as the Beauveria bassiana, and some bacteria. When eradicating tropical sod webworms, it is best to try other avenues that won’t threaten the lives of other beneficial organisms living on your lawn before resorting to the use of chemicals.


The saying ‘prevention is better than cure’ still resonates when it comes to dealing with tropical sod webworms. It is also important that you prevent other issues from affecting your lawn first before taking the necessary steps you are meant to take. Therefore, you must keep your lawn healthy at all times, and this also includes during winter.

Tropical sod webworms affect warm-season grasses, meaning they only thrive in tropical or sub-tropical environments. This also means that they enjoy hot and dry conditions, and the best way to disrupt their growth is to ensure that your lawn is watered regularly. This will make it difficult for the larvae to survive.

It would help if you also made it a point of duty to monitor the level of thatch on your lawn and reduce it when it begins to accumulate. Also, regularly mowing will help to control sod webworm development. However, you should ensure that you don’t cut too much of the lawn as it can give the opposite of the desired result, especially if the grass is too short.

Another thing to consider is the grass type. Some grasses are more susceptible to pest attacks. If you happen to have such grass, getting another species with resistance to the development of tropical sod may prove useful. You may also want to look at artificial grass if you don’t want any pest issue and still don’t mind forfeiting the freshness of grown lawns.

Proper fertilizing will improve your lawn’s health and growth as well as speed up its recovery when attacked by pests such as sod webworms.

When to Seek the Help of a Professional

If you take care of your lawn properly, you may be able to prevent pest infestation or quickly find a solution to the problem. However, if the damage is extensive, especially on large lawns, you may need the services of a professional pest exterminator.

It is essential to note that these services don’t come cheap. Pest management professionals usually put the lawn’s health into consideration when working to remove the pest from the lawn. However, in extreme infestation cases, they may use some chemicals that will help solve the problem but also cause damage to the lawn.

Another place when a professional’s services may be needed is in areas where tropical sod webworms infestation occur regularly. If you notice that your efforts are not yielding any positive result, you should try to seek a professional’s services.


Tropical sod webworms can take that green color and lushness away from your lawn. These pests are attracted to the most warm-season grasses. They lay their eggs on the grass, and the eggs hatch and feed on the grass. It has a parasitic to the grass as they turn brown and dry and eventually die if care is not taken.

Early detection and treatment are among the most effective ways of tackling these insects and restoring your garden to its former glory. You can use different methods to tackle tropical sod webworms, some of which include the use of soapy water, biological attacks, as well as the use of chemicals. Put in measures to monitor tropical sod webworm eggs and devise a means to inhibit their growth.

Place high importance on setting up preventive measures. Ensure that you mow your lawn regularly, but keep the grass at a specific height where it is not too short. Water and fertilize your lawn at the right time, as this will make the growth of tropical sod webworm relatively difficult.

If you feel you can’t handle it yourself, you should call a professional exterminator. The essential thing is to get those insects out of your lawn as fast as possible. Finally, have a good understanding of the biology of sod webworms as it will inform you better on how to prevent and stop their spread.