Rat and mouse activity is usually first noticed in the autumn when rats and mice are looking for a warm shelter where there is food available. Earwigs are hard, flattened, reddish brown insects up to 2.5cm (1in) long. They are harmless to humans and animals, although if handled carelessly, the earwig can give a slight pinch with the forceps. Obviously, it goes without saying that you should use all garden chemicals sensibly. Follow the suggestions and instructions below. Plant leaves can sometimes changes colour or produce unusual marks, blotches or even weird-looking structures on them. Here are some of the more common leaf problems. The most common of all pests and almost every plant from the smallest shrub to the tallest oak tree can be infested.