An ant moat is a simple, effective piece of equipment designed to safeguard feeding stations, commonly used with hummingbird or oriole feeders. This small, cup-shaped barrier is suspended directly above the feeder, creating an obstacle along the hanging wire or hook. The singular purpose of this device is to prevent crawling insects, specifically ants attracted to the sweet contents, from reaching the food source. By interrupting the ants’ path, the moat ensures the nectar or seed remains clean and accessible only to the intended visitors.
The Standard Solution: Why Water Works
The definitive substance to place inside an ant moat is plain, clean water. This substance is effective because it leverages the physical properties of water in a way that ants cannot navigate. When ants attempt to cross the water-filled cup, they encounter a significant barrier related to surface tension.
Surface tension creates a strong, invisible film across the water’s surface. Ants are generally not adapted for prolonged flotation or swimming. When they attempt to cross the moat, they cannot propel themselves across the slick surface or climb the wet sides. Their weight distribution and the moat’s design force them to break the surface tension, resulting in them sinking or drowning, effectively stopping their advance toward the feeder.
Using water offers the simplest, most cost-effective, and safest solution. It is completely non-toxic to hummingbirds and other wildlife that may come into contact with the moat. This method utilizes a physical principle rather than introducing chemicals or sticky substances near a food source. The presence of the water barrier is typically enough to deter the ants from completing their foraging trail.
Addressing Evaporation and Safety Near Feeders
Evaporation and Maintenance
While water is the ideal filler, its use introduces the practical challenge of evaporation, especially during hot weather. Ant moats must be checked and refilled frequently to maintain an effective barrier. In warm or dry climates, this typically requires a daily or semi-daily inspection to ensure the water level remains sufficient.
The water level should be deep enough that ants cannot simply climb down one side and up the other without touching the water. If the water evaporates completely, the ants will cross the dry cup unhindered, creating a pheromone trail for the rest of the colony. Regular maintenance is unavoidable, even for moat designs featuring deeper reservoirs.
Cleanliness and Leveling
Safety near the feeder depends on keeping the water in the moat fresh and clean. Small birds, like finches, are known to drink from the water, making cleanliness important. The moat should be cleaned periodically to prevent the growth of mold or algae, which could contaminate the water source. It is also important to ensure the moat is hung level, preventing accidental spillage or dripping of water into the feeder below, which would dilute the sugar-water nectar.
Common Misconceptions and Unsafe Fillers
Many people consider adding alternative substances to the moat, but most should be avoided due to safety concerns and potential ineffectiveness.
Oils and Detergents
Some recommend adding cooking or mineral oil to the water to reduce evaporation. However, oils can break the water’s surface tension, allowing some ant species to cross more easily. Additionally, oils can drip into the feeder, contaminating the nectar, or attract pests like grease ants, defeating the barrier’s purpose.
Adding liquid soap or detergents to the water is also ill-advised, even though soap lowers surface tension. The primary danger is that a single drop of soapy water splashing or dripping into the feeder can be highly toxic to hummingbirds. Detergents are not meant for ingestion and pose a serious risk if they contaminate the food supply.
Pesticides
Pesticides or insecticides should never be used in or near the ant moat. Any chemical treatment creates an extreme poisoning risk for hummingbirds, which consume a mixed diet of nectar and small insects. The goal is to create a non-toxic physical barrier, not a chemical trap. Sticking to plain water remains the safest and most reliable method.