How many termagant models?

[Merkmon]

Not sure if this is a tactics question but.....how many termagant models am I going to need when a field a tervigon? I have two of the new models and they are astonishing. I would like to use both in a fun list. I have 40 fleshborer termagants. Will I need more? Thanks in advance.

To play competitively (IE : Tervigons), you may want to pick up atleast anothe box of gaunts.

[Transgressor]

I have about 120 or so. I've only come close to running out once against Tau where I had 3 tervigons and they all spawned for 4 solid turns in a row.

With only 2 I'd have about 80 just to be sure.