Giant cockroach is world's heaviest insect? Naw.

...Australia's giants give birth to live young, look after them in a burrow, make "great pets" and dine on leaves.

"Native to western NSW and north Queensland, they can reach 30 to 35g and more than 85mm in length," Sydney University senior biology lecturer Nathan Lo said yesterday.

"They are the world's heaviest cockroach and if not the heaviest of all insects, they are certainly a contender.

"They are different to other insects in a lot of ways and are totally unrelated to the American or German cockroaches found in Australian households."Giants can live up to eight years, which is pretty amazing for an insect.

via Giant cockroach is world's heaviest insect | The Daily Telegraph.

Another site says:

The heaviest insect in the world is the Goliath Beetle. It is found most commonly in tropical African rainforests, but can also survive in many other areas of Africa. Their size does vary with species. The largest species is "Goliathus goliath", weighing on average, 3.5 ounces (nearly 100 grams).

Now THIS is probably the world's heaviest insect species: