Preparing the Jar
Choose a jar with a wide space, such as an 8 oz. jar or larger. Large jugs with screw-on lids also work. Once you find the right jar, use a hammer and nail to create holes in the top of the lid. The jar needs holes to allow in air, since insects live on oxygen, but you also want to keep your insect inside the jar. Measure the holes by the size of your pinkie finger's tip. Any hole larger than this allows smaller bugs to escape. On the outside, paint green grass blades or yellow stars. Add your name in puffy paint to one side to designate your bug jar.
Habitat
The leaves and twigs that you place inside the jar depend on your insect. Pour dirt or sand to an inch from the bottom of your jar. Add twigs, small pieces of fruit, flowers, leaves, grass or particular environment item for your insect. For instance, a caterpillar needs lots of leafy greens to survive. Crickets like to perch on leaves to enhance the vibration of their songs.
Capturing Bugs
For some slow bugs, like caterpillars and beetles, you may be able to simply chase and catch with your hands. However, for crickets and lightning bugs, you need a net with a handle. You also hunt bugs at different times of day. Crickets and cicadas are active day and night, but you'll see crickets better during the day. One way to capture a cricket is by running through the grass with a net and catching while it jumps in the air. For lightning bugs or other nighttime flying bugs, head out at night and watch, then swing your net to capture. Keep your jar close by and hold the net close to the jar. Drop the insect inside and screw on the lid.
Feeding
The food for your insect varies, but at the very least, you need to keep the insect watered. With an eyedropper, squirt small droplets of water onto twigs and leaves for the insect to drink from. Fruit, leaves and decaying plant material are some food types that insects enjoy. Others enjoy nectar from flowers or honey. Check out a book from your library about your insect or study an online source specific to your bug.