Warning: if you love insects, and not just for breakfast, or are of a decidedly pacifistic bent, you may wish to stop reading before reaching the paragraph entitled "Method B". If you cried while watching Starship Troopers every time a Bug got splattered, this node is not for you.
A can of
compressed "air" of the type used for cleaning dust and
gunk out of your
computer can also be used as a handy, makeshift
bug spray,
in certain circumstances.
Method A: Bug Repellant
This one is pretty straightforward. Simply aim the spray (using the little red straw that comes with the "air" canister) at the offending arthropod and physically push it away with the blast of air. Very useful if you've got a window by means of which to defenestrate the creature.
Method B: Cone of Cold
Sometimes a particularly annoying bug will land itself in a place impossible to reach with a bludgeoning object, and will steadfastly refuse to be defenestrated, stubbornly returning to its perch despite repeated attempts to "coax" it away.
Remove the little red straw from the canister nozzle. Observe the "Directions" label on the canister. Notice how it says something to the effect of:
"Always use in an upright position. Tilting or inverting can while spraying will cause liquid contents (white cloud) to be released that could damage equipment."
Ignore this advice. Tilt the canister down (or up) at a decent incline, aiming the nozzle at the little invertebrate wretch, preferably forming a right angle with the surface of the perch, if the perch is a ceiling or desktop. Squeeze the trigger, hard. Watch as a cone-shaped blast of icy cold vapor shreds wings, tears carapace, crushes and mangles the arthropod corpse. Rejoice in your victory.
Note that this should not be attempted on really big bugs, bees, hornets, wasps, tarantulas or 10-foot tall extraterrestrial insectoids. Attempt at your own risk. If these methods are used on hybrid semi-insectoid mythical creatures such as pixies, sprites, or faeries, the author will take no responsiblity for the resulting loss of magic in the world.