Riding lawn mower switchable between mulching and bagging modes includes: a delivery passage for delivering grass, cut by cutting blades in a housing, from the housing to a receptacle by delivering air; and a scroll guide provided in an entrance of the passage for directing the grass clippings to the passage. More specifically, carboxylic acid esters are reacted in situ with an inorganic peroxide such as hydrogen peroxide in the presence of a perhydrolase catalyst derived from a Lactobacillus sp. The main board divides the interior of the housing into a first space and a second space, and there exists a channel opening between the main board and the module so as to communicate the first space with the second space. The pocket panel is thereby secured along both side edges to the sheet body portion, has an open top and thus defines a pocket on the back of the sheet body portion.