Keeping ants out of a hummingbird feeder

The mechanism

An ant moat is a small cup that hangs above the feeder, on the same wire, and holds plain water. Ants travel down from the branch or hook, meet water, and stop. They will not swim it and they cannot go around it.

It is one of the rare pest solutions that is close to completely effective, requires no chemicals, and costs a few dollars. When it does not work, it is nearly always one of the four reasons below rather than a failure of the idea.

The four ways a moat fails

1. It is empty

The overwhelming majority of failures. Water evaporates, particularly in the heat when ants are most active, and an empty moat is just a bridge with extra steps. Worse, it is a bridge you have stopped checking, because you believe the problem is handled.

Fix: top it up every time you refill the feeder, which you are already doing every three to five days. Capacity helps — the Trap-It holds three-quarters of a cup, which is more than most and lasts noticeably longer between top-ups.

2. There is another route in

A moat protects the wire. It does nothing about a feeder resting against a wall, hanging from a branch that touches the feeder itself, or mounted on a pole — ants simply walk up the pole.

Fix: hang the feeder free, with clear air around it, from a hook rather than tight against anything. If you are pole-mounted, the moat is the wrong tool and you need a barrier on the pole instead. Placement.

3. The feeder is dripping

A moat stops ants reaching the feeder from above. It does nothing about the sticky trail leading up from the ground to a feeder that has been dripping nectar onto the grass beneath it. And a leaking feeder is what recruited them in the first place.

Fix: a saucer feeder, which cannot drip. Why feeders leak.

4. Something is in the water

Some people add oil to the moat so it does not evaporate. Do not. Oil in a moat directly above a feeder ends up on the feeder, and oils and petroleum products can damage a hummingbird’s feathers. Plain water only.

Built-in or add-on?

Prefer built-in. The HummZinger line, both Kingsyard models, the More Birds Ruby and the First Nature bases all include one, and a moat you cannot forget to buy is worth a little extra on the feeder.

If your feeder has no moat, an add-on solves it for a few dollars. Look for one with genuine water capacity and open hooks top and bottom — the Trap-It has open eye hooks at both ends and takes almost any hanging feeder.

What not to use

• Insecticide or ant powder. Audubon warns that pesticides can injure, kill and reduce population numbers of birds, bees and other animals. Never near a feeder.
• Petroleum jelly or oil on the wire. It works on ants and it ends up on birds. The same objection as at the ports.
• Sticky tape on the hanger. Traps whatever touches it, which in a garden includes things you did not intend.
• Aluminum foil. A persistent piece of folklore with no mechanism behind it — covered separately.

Keeping the moat itself clean

It is an open cup of standing water in a garden. Tip it out, rinse it and refill it with fresh water whenever you refill the feeder — same visit, ten extra seconds. Stagnant water is its own small problem and a dirty moat is easy to overlook when you are focused on the feeder.