One of the most conspicuous effects of artificial light on fauna is the attraction of moths and other insects by light sources. This can have negative effects on the individual moths, but to what extend artificial light affects moth populations is currently unclear. To investigate possible population effects we monitor moth populations on the experimentally illuminated sites. If there is a significant negative effect of light, we would expect to see a reduction in moth numbers at illuminated, but not at the non-illuminated sites (the dark control). We monitor these moth populations together with the Dutch Butterfly Foundation and many skilled volunteers. Moths are trapped during a number of nights during early summer and summer, and released after identification.