Bugs are simple creature that can do complex things. Therefore robotic bugs are a good way to design simple robots to do some basic behaviors, while still completing complex tasks.
Look at Roomba, for example: it looks like an ant when it bumps everywhere looking for more food all the time. Well it was actually inspired by insect behaviors.
First, let's see the best research robots, like the butterfly robots that really fly. Then there are many cool robot toys based on bugs, but they are simple and fun.
Bugs are a model of how simple design can achieve complex tasks. Scientists have been searching for years how the ants were able to organize themselves. It even gave birth to new fields like swarm robotics (where you try to let 100+ robots organize themselves without centralized command center) and ant colony optimization, which is a swarm theory directly inspired by the study of ant colonies.
Another impressive research are the butterfly robots. Some of them weight less than 1 gram, and are still able to fly. This is possible thanks to the progress in micro-electronics. The main research is actually on making always smaller sensors and actuators as much as it is on making wings that fly.
RC Butterfly Robot, By Proxdynamics
The picture above is an RC butterfly robot. That means you can control it well enough to fly inside a room. It weights only 1.1 grams.
Yes, these cybernetic bugs are not just the creation of some mad scientist, they already started invading our homes years ago.
While the most populars are probably the Hexbugs, there are many cool robot toys in the form of bugs. Hexbugs come in many different forms: hexbug nanos are the small vibrating one, but you also have the Hexbug Ants that react to touch, the Hexbugs Spiders are remote controlled...
Also, you can find quite a few beginner robot kits that look like bugs. Actually, for every hexbug that exist, you could find an equivalent robot kit to build it yourself.
Be careful though, many kits that cost around $10 are cool to make, but also very fragile. So handle with a lot of care, or invest a little more money into better quality.
Other pages that may interest you:
Animal robots inspired by nature. Find out how nature and animals have inspired the greatest robotic designs.
My list of top robotic pets. Find out the Top 10 robotic pets. It covers all price range and abilities.
The dinosaur robot pets. Check out the Pleo and Little Inu robotic pets. Cheaper than Aibo, and still a lot of awesome features.