Thanks patrickfraser.
Here's what Peter Clausen said in that thread:
"Rank is on the left. Number of posts required to make the rank is the number on the right.
Example: A new member is an ootheca. When they contribute 20 posts to the forum they become 1st instar.
ootheca 0
1st instar 20
2nd instar 40
3rd instar 60
4th Instar 100
5th instar 150
6th instar 225
7th instar 350
Mantis 500
Flower Mantis 750
Unicorn Mantis 1000
Dead Leaf Mantis 2000
Ghost Mantis 3000
Devil's Flower Mantis 4000
Orchid Mantis 5000
Enigmatic Mantis 10000"