A cartridge is described which is packed with a composition which comprises a mixture of at least one aliphatic aldehyde in the range of two to seven carbon atoms (C.sub.2 -C.sub.7), at least one sulfide or disulfide, ranging from one to fourteen carbon atoms (C.sub.1 -C.sub.14), at least one carboxylic acid, ranging from 4 to 6 carbons atoms, in an appropriate carrier. The use of at least one diketofuran of 5 to 7 carbon atoms is optional. The cartridge is provided with a dispensing nozzle to apply the composition to a tree trunk in the form of a closed band. When so applied, it prevents Gypsy Moth larvae and other hardwood defoliators to ascend the tree and thus interrupts the feeding cycle of these defoliators.