Army Worms

Army Worms

Army Worms This year in Australia, ideal weather conditions have created a continued life cycle for the aggressive Army Worm.

Summertime is often when Army Worms appear in plague proportions and leave brown patches all over your lawn. 

However, this year the plague proportions of Army Worms are continuing into Autumn.

These hungry little sucking caterpillars are another type of lawn pest which are commonly referred to as lawn grubs. The worm infestations can pose a threat to all lawn types if left untreated.

What Are Army Worms?

The Army Worms only eat healthy grass – so if your lawn is the best-looking turf on the street watch out!

In short, the Army Worms find the best, luscious looking turf in the street and feed on it – once done, they continue onto the next healthiest looking lawn and so on.

This caterpillar/grub, from the Spodoptera mauritia moth, is most prevalent throughout the warmer months of the year, and with continual conducive conditions repeats infestations can occur.

What Damage Do They Cause?

Lawn Damage Caused by Army WormsThe damage caused by Army Worms is most obvious by the speed at which damage occurs, as the caterpillars form very large numbers and behave like a colony to eat away at the green leaf of lawns.

Army Worms can vary in colour from green to brown to black, they can reach a maximum length of about 4 cm, and will become plump as they feed and mature. These large numbers are possible due to the moth parent being able to lay up to 500 eggs in a single laying, and then repeat the same process the following night.

This lawn grub gets its name because it forms a large army, lays devastation to an area, and then quickly moves onto the next lawn once it has laid waste to yours.

In fact, the mother moth can often be seen laying eggs under the eaves of your home!

Army Worms can also attack many other types of plants and vegetables, and the key to effective treatment is to identify and kill them as early as possible.

Do I Have Army Worms?

Lawn Worms in Grass

How to Tell If Your Lawn Has Army Worms

Army Worms are very difficult to find, they spend their days hiding at soil level, and deep inside the thatch layer of the lawn.

It’s at nighttime that Army Worms will come out and spend their entire night feeding on your lawn.

For this reason, it can be difficult to actually track down these lawn grubs and pin the proper responsibility on them for the damage to your lawns.

When seeing that your lawn is becoming damaged in large spread-out areas, then Army Worm damage should be considered as a possibility.

Not only could the damage be caused by Army Worms, but it may also be due to another lawn grub such as Sod Webworm.

Testing Methods to Check for Army Worms

There are two main methods of checking for Army Worms.

Method 1:

The first method involves using a bucket of soapy water that has been mixed up with dishwashing detergent. The mixture is then poured over the lawn in a small area. The area is then monitored over the next 10 minutes to check for caterpillars that are rising to the surface.

Method 2:

The second method involves going out onto the lawn at night time. With a good torch in hand, get down low onto the lawn and carefully run the torch over it looking for caterpillars feeding or moving. Begin the search at the damaged area of turf, and spread outwards from there.

Other Potential Signs

Army Worm MothsAnother sign of possible caterpillar infestation is to leave the outside light on at night for a few hours. Then go outside every so often and check for moths flying around the light.

If a multitude of moths is present, then this may be a sign of possible lawn caterpillar problems which will require further investigation.

If you do find caterpillars, it would be best to capture a few to take to the local nursery for positive identification. This will help the staff member to recommend the right insecticide for the caterpillar type.

How to Kill Army Worms

Once Army Worms have been identified, they are treated with a lawn insecticide which is freely available for purchase from online garden stores and nurseries.

myhomeTURF also recommends using Acelepryn an effective insecticide that can be purchased through our myhomeTURF online store.

The insecticide is mixed up and applied to the lawn just before dusk. Ensure to allow yourself enough time to finish the entire lawn treatment before dark. The treatment is then lightly watered into the lawn so it can reach down to the base of the thatch layer. The poison is then ingested by the Army Worms as they are feeding on the lawn. Be careful not to overwater, this will simply wash the poison away, and it will not be ingested by the caterpillars.

A spray kit is a fast and effective way to apply all your liquid lawn care products; an easy-to-use option is the Solo 7L Manual Sprayer that comes with a quality pressure sprayer. Spray indicators such as Blazon allow you to clearly identify where you have applied the spray. myhomeTURF also recommends a surfactant such as the Wetter 600 to increase the activity and efficiency of liquid chemicals.

Recommended Products

Acelepryn GR

Acelepryn GR 10kg Bag is a superior granular formulation that is unmatched in controlling season long grub and caterpillar control in one single application. Acelepryn GR 10kg is suitable for ZoysiaKikuyuCouch and Buffalo grasses. Always read the safety directions and instructions on the product label before use.


Indigo Rumbler 100SC 5L

Indigo Rumbler 100SC 5L is an effective broad-spectrum insecticide in a suspension concentrate formulation which contains the active ingredient Bifenthrin (100g/L). Indigo Rumbler 100SC is suitable for use on Zoysia, Kikuyu, Couch and Buffalo grasses. Always read the safety directions and instructions on the product label before use.


What About Repeated Infestations?

The life cycle of the Army Worm, and its Moth parent, is very rapid, and as such, it is possible that three different infestations can occur over the warmer months of the year.

Be aware that this is a possibility, and if the same symptoms do re-occur then the same process of identification and treatment should be repeated as soon as possible, and when necessary.

Repairing damage from Army Worms

Army Worms will not generally kill a lawn by its feeding, but it will become heavily damaged, which if left untreated could cause patches of lawn to die. The only real thing to do at this time is to follow good lawn care practices and apply a quality fertiliser, and ensure it is getting adequate water. This will allow the lawn to best repair itself.

There is no need to over-water or apply excess fertiliser, doing either will not aid the lawn in repair, but may even cause further damage. Always apply fertilisers at the manufacturer’s recommendations.

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