Fall Army Worms

Fall Army Worms in North Florida Lawns

Checking Insect Numbers In the Lawn:

 Scouting the lawn for Fall Armyworms and the signs of damage they can do should be done frequently to carefully monitor both harmful and beneficial insect populations.



All armyworms are light brown moths with a wingspan of about 1 ½ inch the fall army worm has a noticeable white spot near the wing tip. Caterpillars are about an inch and a half when mature and are a pale brown to black with stripes along their sides. Immature caterpillars are a olive grayish green and have a stripe that runs along their back. A prominent inverted white Y on the head of the caterpillar makes it easier to identify  from other similar pests or armyworms.

Damage to Lawn Grass by Fall Army Worms:

Larvae of the fall army worm when in the more immature stage feed only on one side of the leaf blade leaving a transparent area on the leaf blade but more mature caterpillars will consume entire areas of the leaf. When food supply becomes depleted in large populations army worms will move locations in masses making a little army of moving caterpillars giving them their name.

Feeding Habits of Fall Army worms: 

    Fall armyworms are pests primarily on Bermudagrass, although they can damage legumes, some vegetable and fruit trees and flowers as well.  

Reproduction and Life Cycle in Jacksonville | St. Augustine | North Florida Areas:

 Fall army worms migrate long distances. Life cycles begin in the spring when migrations reach the US or when overwintering pupae emerge as adult moths. Several generations of armyworm will occur each year with the life cycle form egg to pupae only lasting a few weeks. Fall armyworms pupate in the soil in loose cocoons. 

Control for Fall Army Worms:

            Natural Control: 

Predacious earwig, several spiders, ground beetles and parasitic wasps all help to keep populations of lawn caterpillars in check.  

Cultural Control:

Check for insect populations using a flashlight at night or the can flush method. 

Studies throughout Florida have shown significant decrease lawn caterpillars by maintaining proper cultural procedures. See reducing the need for chemical control.  

Chemical control: 

     When no beneficial insects are found and lawn caterpillars reach more than 10 per square foot then chemical control may be necessary. Thuricide, Diazanon, Sevin or Dursban may be used in accordance with package label directions for sod webworm treatment.  

 A Word of Caution from Me to You: 

     Perhaps it is my many years of dealing with the people in the Agriculture industry who have lived long lives and encountered many troubles with chemicals during their careers, but I cannot talk about chemical control without at least my mentioning the following concerns. 

 Make sure to read all directions carefully and apply liquid sprays diluted with water at the application rate recommended on the product label for the pest you are targeting and do not mix stronger than suggested target treatment rates. 

      Remember that insecticides are POISONS and approach their use with caution, wear protective eye gear and chemical resistant gloves and rubber boots as well as long sleeved shirts and pants. Remember to wash these items separately from other laundry immediately after application and shower after getting the clothes into the laundry. 

Lastly but most importantly, pay particular attention to lock unused chemicals up away from visiting children and pets.  

So that’s it on the speech about chemicals, I hope I have been able to help you know what’s wrong and how to treat it so now you have to help me sleep easier by indulging me with these motherly concerns, fair trade don’t you think?  I’ll sleep easier knowing that you did.