Horses and flies

05mei2011
Source: levendehave.nl
Biting flies prefer dark-coloured horses; this is probably no surprise to horse owners. A team of researchers from Hungary, Spain and Sweden has now studied why this is so.
During the study, black horses were bitten 25 times more often, and brown horses 15 times more often than white horses. This preference has to do with the reflection of polarised light. The polarised light reflected by the horsehair determines for a fly whether the animal is a potential host for a (blood) meal. The more polarised light there is, the more interesting the host. Dark coats reflect more polarised light than white coats do.

A white or light-coloured coat is, however, not only beneficial. Horses with lighter coats are more susceptible to sunburn, skin problems and skin cancer. Furthermore, their increased visibility in the wild makes them easier prey.

The scientists carrying out this study expect that a similar effect can be found in other animals. Light-coloured animals are bothered less by flies than animals with dark coats.