There isn't very much information out there about the Mantis Warriors as they're a pretty minor chapter (aside from IA 9 & 10), but what is out there has detailed the Praying Mantidae pretty well. They're a small sub-unit of the Mantis Warriors who have succumbed to the chapter's gene-seed flaw. They see everything basically in tunnel vision - this puts them in a Matrix-style bullet time state where everything is slowed down.
I had decided I wanted to create some Praying Mantidae and use them as sternguard. Cerberus was ordering some FW items and I can never pass up an order, so I picked up these when he ordered his titan and contemptor.
I was originally going to paint them yellow with green, but the yellow primer just didn't work out well. I stripped them as best I could with Simple Green and primered them green. Their helmets didn't strip well at all so I purchased some MK2 helmets from a seller on Ebay. I like these a little bit better.
I don't know if it is the smaller size, the resin, or what, but the details just didn't 'pop' for me on these models. I'm not super happy with how they turned out but I feel like they'll fit well as sternguard. They're using Ferrus bolters. I chose these because they have the really cool scope on top.
Cvinton at Dark Future Games created some 'maggot' bases that I used as grubs in a jungle for this squad. They're marching through, purgin' xenos, and have stomped their way into some kind of grub hideout.