Only thought about putting a post up on this work in progress after I was most of the way through. I picked up 20 Lotus seed pods from a flower wholesaler (about 10 euro). I have been playing around with them and my Bitz box for the last few days.
As per the advice from http://ifitwasntforone.blogspot.ie/. I coated these with watered down PVA glue which has helped stiften them up and help paint to stick (took ages to dry). I have gone with a yellower base colour than my brown tyranids as I went the bugs crawling out of them to stand out.
More about Mike's Tyranids can be found on http://nidomnom.blogspot.ie/