A tiny bug in your home could be one of millions of species. Most of these are harmless, but a few kinds are damaging to your house, can multiply to the point they become a nuisance or bite people and pets. You might not be able to identify your bug precisely, but you can narrow the possibilities down to a group of bugs and check it is not a pest species. If you are still very curious, you probably need to kill the bug or take a very close-up photograph and send it or the photograph to an expert.
Catch the bug in the box, using the piece of paper to slide the bug in. Put the lid on the box if the bug has wings or seems able to crawl up the sides.
Examine the bug with the magnifying glass.
Count the number of legs the bug has. Insects have six. Arachnids like spiders and mites have eight. A creature with more legs than you can count is probably a centipede or a millipede. Bugs that look like maggots or caterpillars are insect larvae.
Check that the bug is not a pest species. The main ones to rule out are bed bugs and fleas, which require treatment if your house is infested. These are both insects. If your bug is an insect, compare it to photos in an identification guide. Ticks, which are arachnids, sometimes bite and spread disease but are rarely found inside.
Place the ruler underneath the box. If the bug is slow, tip it onto the paper and place the ruler beside it. Alternatively, put a penny or dime in the box.
Take several close-up photos of the bug and the ruler or coin to show to an expert or to post on an identification forum online. To find an off-line expert, contact a local museum, university or entomology group. It is almost impossible for amateurs to accurately identify most tiny bugs..