The word 'Pooter' has several meanings. The first, and most common, is a way of shortening the word 'computer', by people who think that they're being cute. Another use of the word is mostly confined to biologists, and is a description of a piece of scientific equipment.
Pooters are used for catching small insects, arachnids, crustaceans, and any unidentified wriggly things, collectively known in the scientific community as 'bugs'. By definition, these bugs are very small, and in addition to that many of them sting, bite or ooze at you when feeling threatened. In short, they can be difficult to catch, which is bad news for scientists and children (who frequently like to catch bugs, either to examine, or eat).
Pooters make bug-catching much easier. They are very simple devices, and also very cheap, if a little difficult to get hold of. The main part of a pooter is a clear plastic cylinder. This is the bit the bugs go in. On top of the cylinder there are two holes, with a tube coming out of each of the holes. One of the tubes is short, and has a gauze or membrane at the cylinder end, while the other tube is long, bendy and has nothing at either end.
To use a pooter you first have to find a bug. If there aren't any on the ground, try standing underneath a tree, holding a sheet of paper out and shaking a branch. Lots of things should fall down, including a few bugs. Place the long tube of the pooter over a suitable bug. Then put your mouth to the end of the short tube and inhale sharply. If all goes to plan the bug should be sucked up the long tube and into the cylinder.
It's natural to feel a few qualms about doing this for the first time. The membrane stops the bug from being sucked into your mouth, but this doesn't stop most people being convinced they're going to swallow it. As long as the pooter is used properly the bug should be captured by the cylinder.
There is one very important thing to remember: always make sure you're sucking the correct tube. Sometimes the tubes can be very similar length, and if there are already bugs in the pooter when you're trying to catch another, there is a risk of inhaling one (or more) of them.
Technological Advances and a Warning
The pooter is a very simple device, but even so it has been affected by progress. There are now mechanical pooters, which do the inhaling for you. These are used in industry as a safety precaution, because the membrane that stops bugs won't stop dust, mites and insect scales getting through. These can cause allergies, and may have nasty long term effects.