Tartago® water-tray harp kit: harp, 15 W solar module and tray

01 · HOW IT WORKS

It attracts nothing — it sits in the flight path

The harp has no attractant, no light and no bait, and that is the question asked most often. The hornet hunts by ambush: it hovers in front of the entrance waiting for a forager returning loaded. The harp goes parallel to the entrances, across that flight corridor, and the hornet is electrocuted crossing between two wires 20 mm apart. That spacing is what makes it selective: the hornet is considerably bigger than a bee and bridges both wires, while most bees pass between them without closing the circuit. Placed too close to the entrance, or side-on, it intercepts nothing — and then it looks as if the device is not killing, when what is wrong is the siting.

02 · ASSEMBLY

Reckon on an afternoon in the workshop the first time

Better said upfront: assembly takes time. The wires are fitted and tensioned one by one onto the insulators, and anyone who is not handy will spend the afternoon on it with the video running. It pays to do it properly, because a slack wire or a badly seated insulator is behind almost every earth leak. Two tips from people who have built one: screw the feet to a board — they come pre-drilled for it — because on farmland the assembly is tall and the wind moves it; and follow the manual's order on the electrical side, which is what keeps the insulation working in the rain.

03 · THE KIT AND HOW TO EXPAND

One module powers up to five harps

The kit contains harp, 15 W solar module and tray, and that is all it needs to work without a socket. There is no battery, so it runs on daylight. The module can power up to five harps in parallel, so to expand you only need, per additional harp, the bare harp, its tray and a female/female extension to join it to the previous one; to move the module away from the harp, the extension is the male/female one. Connections use moisture-proof connectors, and the module has a shut-off button with automatic discharge: switch off before touching anything.

04 · THE TRAY AND YOUR CONTROL FIGURE

A few drops of soap, and count what falls

The water tray catches what falls electrocuted. Add a few drops of washing-up liquid: it breaks the surface tension and stops a stunned hornet from floating off. A finger of water is enough; what matters is that the surface is unbroken. The tray is also your measuring instrument: on a well-sited harp the reference ratio is 4 or 5 bees per 100 hornets. If you are pulling out many more bees than that, the harp is in the wrong place and needs moving.

ELECTRICAL SAFETY

This is electrical equipment left outdoors. Switch it off at its button before handling the harp, the tray or the wires, and never assemble it with the module connected. The button discharges automatically, so once off the circuit is dead.

05 · WATER OR DRY

If you would rather not depend on water, there is the dry kit

The dry kit has the harp with a hopper instead of a tray, and the solar module with lithium battery. The two harps differ in this:

Everything else is the same: 60 cm wide, 0.35 mm stainless wire at 20 mm and the same electric modules.

06 · BEFORE YOU BUY

Harps work mainly in summer and autumn, when hornet pressure builds; set up early they cut that pressure before the nests grow. And it helps to know what they are: a measure to protect the apiary, not to eradicate. They reduce attacks at the entrance; they do not remove the local population.