An insert apparatus for placement in a rain gutter includes a porous insert body including a plurality of randomly arranged filaments attached to one another to form a mat. The insert apparatus is shaped to fit within an inside channel of a rain gutter. Optionally, the apparatus may include a cover panel, comprising a screen, attached to the top of the insert body. In use, the insert apparatus is placed inside of the gutter channel so as to substantially fill part of the channel, and to block entry of debris into the gutter. When placed in the gutter channel, the insert apparatus substantially prevents foreign matter such as leaves, twigs, pine needles, etc, from collecting in the channel. The insert apparatus may be configured to leave an open flow path therebelow when installed in the gutter.