The invention is a vermicomposter which is a composting device that uses earthworms or worms to accelerate the composting process. A multiple tray system is used to greatly increase compost production and for convenience of compost harvesting. The invention uses thermal siphon airflow and light-tight air permeable connections between its members to increase compost production. The vermicomposter comprises: a base with collection tray, at least one stacking tray, and a light-tight air-permeable lid. The upper surface of the base forms the collection tray which comprises: a set of sides, a bottom, a set of support ribs with notches, and is open on the top to form a liquid-tight container. Notches are sectioned out of the upper inner corner of each support rib. Each notch defines on the rib: a notch bottom surface, a notch side surface, a side vent distance, and a lower vent distance. One mode of the invention further comprises a worm ladder which comprises: a horizontal flange, at least one ramp, and large void area. A stacking tray comprises: a wide brim, a set of sides, a bottom, and is open on the top. A light-tight air-permeable lid is used to cover the upper most stacking tray and provide a light-tight air-permeable cover for the device. The lid comprises: a large dome area, a wide brim, a skirt, a set of vertical support ribs, and a set of lateral support ribs.