An image display medium capable of displaying an image showing little change of the image density, and also little change of the image density uniformity, and being stable in density contrast, even when repeatedly rewritten over a long period, and an image formation apparatus are provided. The invention also relates to the use of the combinations for controlling animal pests and unwanted vegetation and to the corresponding methods. The overlay region may be divided into a plurality of partitions. The measurement arm is slidably supported on the clamp.