@ Fiorite- There are a lot of categories that you could separate the world's largest insect title into.
The longest insect is the Chan's Walking stick, which stretches almost two feet in length. London's Natural History Museum has a specimen that is 55.6 Centimeters long when the legs are outstretched. The bug is likely found in the treetops of the Borneo forest.
Other Giant crawling critters are as follows:
Giant South African Earthworm- average 6 feet largest confirmed specimen 22 feet.
Goliath Bird Eating Spider- Largest Specimen was 11 inches across.
Titan Beetle- It can grow to nearly seven inches, all without eating during its adult life cycle.
Queen Alexandria Birdwing Butterfly- can have a wingspan up to 12 inches.