Animals, like people, tend to choose mates based partly on body symmetry. Today’s invention is a rat trap which aims not to kill any animals, but to reduce their reproductive attractiveness.
A narrow box has one-way gates at both entrance and exit. A rat (or mouse) is attracted to the smell of some bait and as it passes along inside the box, it triggers a small aerosol paint spray. This contains a harmless but longlasting dye which creates a striking pattern on one half of the rodent.
This might take the form of a high-contrast ‘dazzle’ camouflage or zebra stripes, but the idea is that by making rats of both sexes look strongly asymmetric, they will be much less likely to be chosen to mate.
This device can, using a small reservoir of attractant scent, allow hundreds of animals to pass through every hour.
By lowering the reproduction rate significantly in this way, the rise of rodent plagues (which consume 16% of rice produced in Asia) can be avoided.