An easy and safe way to clear dirt and bugs from outdoor lights that have open bottoms is first of all, turn the light off. Then, unscrew and remove the bulbs so you can de-gunk them with foaming glass cleaner. Set aside. If the lights face up, cover the socket with a rubber covering such as chair leg tips to protect the socket from wetness. Now spray the foam glass cleaner on the inside and outside panes. If needed, use a dish scrubber with a handle and rinse off with a spray bottle filled with water. Let dry. If the sockets face down, and cannot be capped, apply cleaner to the scrubber and work around them. When completely dry replace the bulbs and you should have a bright light shinning outside.