Hay is dried forage, typically made from grasses or legumes like alfalfa, which is cut, cured, and baled for livestock feed. While curing removes moisture, the resulting product remains an organic material that frequently attracts various organisms. Hay is highly susceptible to infestation by numerous pests, including insects, mites, bacteria, and fungi, especially when improperly stored. Understanding the specific properties of stored hay that make it a target is the first step in protecting this valuable resource.
Biological Reasons Hay Appeals to Pests
Hay bales represent an attractive habitat because of the residual moisture and heat they retain, even after proper curing. Although cured hay should be baled below 20% moisture, this water is enough to support microbial life. Microorganisms like bacteria and fungi metabolize residual sugars and starches in the forage.
This microbial activity, known as “sweating,” generates heat, which quickly raises the internal temperature of the bale. This warmth creates an ideal microclimate, attracting arthropods and accelerating insect reproduction cycles. The forage also provides an abundant source of cellulose and nutrients that many pests consume.
The physical structure of stacked bales provides shelter and protection. The dense, layered material offers countless dark crevices where pests can hide, nest, and breed undisturbed. This combination of a stable food source, elevated temperature, and secure habitat transforms the hay stack into a highly desirable environment.
Specific Pests Associated with Hay Storage
Pests that infest stored hay are primarily attracted by high moisture or the hay’s nutritional content. Grain mites, for example, are tiny arthropods that thrive in warm, humid conditions, feeding on mold and fungi. Large populations of these mites leave behind a dusty residue and may cause dermatitis in people handling the hay.
Other common insect pests are various species of beetles and moths. Darkling beetles (mealworms) consume cracked grains and fines within the hay. The Indian meal moth and the clover hayworm moth infest hay, with their larvae spinning silken webs that bind the forage and accelerate spoilage.
The damage caused by these insects and mites reduces the hay’s palatability and nutritional quality for livestock. Rodents like mice and rats also seek out hay for nesting material and warmth. Rodents cause significant damage by burrowing and contaminating the forage with droppings.
Essential Storage Techniques for Pest Control
Effective pest control relies on managing the storage environment to remove the factors that attract these organisms.
Elevating hay bales is a foundational practice, as storing bales directly on the ground allows moisture to wick upward, promoting mold and heat generation. Using pallets, crushed gravel, or concrete pads helps create a drainage layer and keeps the forage dry.
Proper ventilation is necessary to dissipate heat and reduce the humidity that supports pest reproduction. Bales should be stacked to allow for air circulation, leaving small gaps between rows and avoiding stacking hay directly against exterior walls. Stacking rectangular bales vertically on their short end minimizes the surface area available for rodent tunneling.
Routine monitoring allows for early detection of potential problems. Regularly checking the hay for signs of dampness, mold, or insect activity is important for maintaining quality. Using a hay temperature probe to monitor the internal core of the stack can detect excessive microbial activity before it leads to spoilage.
Minimizing access points helps exclude larger pests like rodents. Sealing cracks, holes, and gaps in barn walls and doors prevents entry and reduces the likelihood of nesting. Focusing on dryness, airflow, and physical barriers makes the environment less hospitable, significantly reducing pest attraction.