Army worms are not true worms but the larval stage of several moth species belonging to the family Noctuidae, including pests like the True Armyworm and the Fall Armyworm. They earn their name from their tendency to “march” across fields in large, dense groups when their initial food source is depleted, seeking new vegetation. This article investigates the direct threat these common pests pose to human health compared to the economic harm they inflict.
Do Army Worms Bite or Sting
Army worms do not possess the biological mechanisms necessary to bite or sting humans, nor are they poisonous to people or pets. As larvae, their anatomy is designed exclusively for consuming plant matter, using chewing mouthparts to rapidly defoliate grasses and crops. When disturbed or handled, their defense mechanism is to curl into a tight “C” shape and remain still. They are focused solely on feeding and growth before pupating into adult moths.
Contact Reactions and Allergies
While army worms do not bite, contact with their bodies or shed materials can sometimes lead to mild dermatological reactions in sensitive individuals. The larvae are covered in fine hairs called setae, which can cause irritation upon direct contact. This physical interaction may result in contact dermatitis, characterized by localized symptoms such as itching, redness, or a minor rash. Reactions are typically mild and temporary, resembling irritation caused by handling other non-venomous caterpillars. A secondary risk is the inhalation of shed larval skins or dried frass (droppings) in environments with severe infestations. This airborne exposure can trigger respiratory allergic symptoms, such as coughing, sneezing, or wheezing, particularly in people with pre-existing sensitivities.
The True Scope of Army Worm Damage
The threat posed by army worms is economic, stemming from their rapid feeding habits on agricultural crops and turfgrasses. The larval stage is the most destructive, as a caterpillar consumes approximately 80% of its total lifetime food intake in the final two or three days before it pupates. Army worms target grasses, including major cereal crops like corn, wheat, barley, oats, and rice, in addition to turfgrass on golf courses and residential lawns. The damage is often characterized by leaves appearing ragged and skeletonized, with only the midribs remaining. In mature crops, large caterpillars may chew through the stems just below the seed head, causing the grain to fall to the ground, resulting in financial loss for farmers.
Safe Management and Prevention
The safest approach to managing an army worm infestation is to minimize direct skin contact, especially when dealing with large numbers. When treating an infested area, wearing gloves and long sleeves helps prevent mild skin irritation from the larval hairs. For small patches, non-chemical methods like sweeping the caterpillars into a bucket of soapy water can eliminate them. Homeowners can focus on prevention by maintaining a healthy lawn, as army worms often gravitate toward stressed or thin turf. This includes proper fertilization and ensuring the grass is mowed to the recommended height, typically between two and three inches. Introducing biological controls, such as beneficial nematodes or encouraging natural predators like birds and parasitic wasps, provides an effective, non-chemical control strategy. If a widespread infestation occurs, contact a professional pest control service or a local agricultural extension office for targeted treatment with products like Bacillus thuringiensis (Bt) or appropriate insecticides.