If you survive to the part were these guys spawn you need range wepons like snipers but do keep melee as well for defense unit. If you think this is good information please up this

If you see it kill it for element

Get one Rockwell and kill that terd.

Bleep bloop bloam, no more to roam, this drone done killed ya, you ain’t making it home.

In my previous experiences I found that rockets and snipers are highly effective but when shooting them watch out for approaching defense units so you don't get hoarded.