In agricultural areas, butterflies rely on human activity, as in this way their habitat is created and maintained. In the extensively farmed lands of southern and eastern Europe, many butterfly species can be found in high numbers. However, high fertilizer application and low ground-water levels in the intensively farmed land of northwestern Europe have caused the extinction of many species. In landscapes created by modern agricultural practices, there are only a few species left, such as the common Cabbage White and nymphalids, like the Peacock and Small Tortoiseshell. Over all of Europe, abandonment of agricultural land is posing a serious threat to butterfly diversity. Semi-natural vegetation that provides some refuge, has almost disappeared. Nowadays, it is maintained in nature reserves and found on road verges and along ditches ( C-8).