Rare forest pests

The examples of the development of foci of mass reproduction of forest pests, which are rare in most of their range, are considered. Some of them are included in the red books of Russia or its regions. The reasons leading to the emergence of foci of such insects, as well as the patterns of development of outbreaks of their numbers, are not known. Some of the considered species of insects formed foci in small areas (once or over several decades), while other phytophages realized outbreaks of mass reproduction in vast territories and caused significant damage to forage forest species. Difficulties in determining the species of rare phytophages sometimes lead to the fact that that extermination measures are being carried out against them, while these insects are listed in the red books. It is indicated that the rare occurrence of outbreaks in some species of forest pests on a part of their vast range has not been scientifically substantiated to date. This does not allow making informed decisions on the organization of measures to protect forests from rare forest pests, since there is no motivation for organizing monitoring of identifying their foci.