In nature they feed on a many different types of insects and insect larvae, worms, very small fish and algae. Most people who fish for bluegills will use earthworms or nightcrawlers but worms are not the only effective baits. Crickets, grubs, meal worms, pieces of hot dog, even small minnows can be effective.
In general, you will likely have the best success fishing for bluegills with live bait by using a thin streamlined bobber that the fish can pull underwater with little effort. Also be carefull not to use too large a hook or you bait will be stolen, a size 8 or 6 will work well. I prefer a size 6 aberdeen hook no these lousy so called bait holder hook which are harder to remove and invariably duller.
In early spring, even the larger bluegills will be in very shallow water sometimes within inches of the shoreline where the water is comparatively warm. Later in the spring, they will start selecting spawning terroritory. Once spawning begins these fish tend to become more careless and aggressive.
The key to success, is finding where in a body of water that the fish are spawning.
If the water clarity is good, it is often possible to see dinner plate sized depressions in the pond or stream bottom, which are nests excavated by spawning bluegills.
Casting a lure in the vicinity of these nests has a high probability of triggering a strike
During the early summer bluegills can be found in water 18 inches to 4 feet deep, wherever there is some sort of structure such as lily pads, rocks or debris. As the water gets hot the larger bluegills will go deeper, venturing into the shallows only as the sun goes down.
In the fall bluegills will migrate to the shallows as the water cools.
Using Artificial Lures for Bluegills
In general, the more popular lures for bluegills are lead head jigs in the 1/32 oz to 1/8 th ounce range with with rubber grubs 1 - 2 inches long. For most situations, I favor the 1/16 th ounce jig with a black or chartruse 2 inch long soft plastic twirltail. Inline spinners in the 1/16 to 1/8 ounce range are also a good choice on open water. I have had better success fishing for bluegills using inline spinners with gold colored blades than with silver colored.
When fishing with artificial lures, it is very important to retrieve the lure very slowly. Bluegill are unlikely to try to chase down a lure traveling at high speed.