Weigh the bottle down with a decent sized rock, so your little friend can't move it around. Adjust the bottle so the cut end is facing slightly downward, so food gets trapped in the end. ONLY feed them in the bottle - use a dropper or turkey baster to squirt the food into the far end of the bottle... wait with a net and when he goes in the bottle, use the net to block his escape. Its important that you have a net larger than the mouth of the bottle. How large is the damsel?