Classical landscape ecology views spatial heterogeneity of habitats at relatively large 'human scales', and it is at such scales that most decisions of land management and nature conservation are made. The present paper makes use of a wider range of spatial scales to examine land mosaics from the 'fly point of view'. Taking examples from the Diptera faunas of mountainous land mosaics, it is demonstrated that: (i) large scale, 'patch content' landscape management has a direct bearing on Diptera community structure, (ii) borders between large scale patches are not necessarily perceived by flies (or other insects) in the same way as we perceive them, (iii) border complexity between patches at any scale may be as important as patch content as an axis of habitat definition. In this sense, 'border' is not to be confused with 'edge effects'. It is concluded that attention to both patch content and patch border complexity of land mosaics, viewed at the relevant spatial scales, is necessary for future successful conservation of Diptera biodiversity and for the efficient use of these insects in environmental assessment studies.