The 'largest' (heaviest) insect may be this newly discovered 'Wetta', a type of tree dwelling tropical cricket. It is the size of a large rat. Here is the news story and some snaps.
The Web is Bugging Out Over Monstrous Insect Discovery | Trending Now - Yahoo! News
Yes. A cricket the size of a large Hamster. And there you go. :shock:
It may not be the longest but they are saying it is possibly the heaviest yet discovered. Found in a tree. In NZ.