An edible plant-extract-based insecticidal composition comprises d-limonene, a non-toxic hydrophilic solvent, and an amount of a polyethoxylated castor oil sufficient to solubilize the d-limonene in the hydrophilic solvent. Mixer elements may be disposed along the flow path to disturb the sedimenting particles, to release entrained lighter particles. The front upper panel includes a body portion, and an extending piece extending from one edge of the body portion. The ability to rotate the shelf relative to its mounted first edge allows easy leveling of the shelf by adjusting the hanging length of the flexible members suspending the second edge of the shelf.