EA Staff (Retired)you don't attack them at that early stage, you just hold back and defend the places that are important since scarabs don't win when they have to do the attacking, at the very least it stops them from taking out harvesters, holding down a bunch of platforms, and the like.
EDIT: Oh, and strongarm turrets are a pretty decent way to get rid of them too, not quite as efficient as riflemen but if you catch them by surprise while they're moving its no contest and if they trade with the turret its a relatively (but not quite) even trade
Despite the tiberium lead, I would rather be the player with the additional unit on the field.
Scarab users tend to be a bit greedy and double up on harvesters so the minor tiberium lead you seize is very short lived.
Also just a heads up everyone, please take what I say with a grain of salt. I am still learning this game.
If you have either cheap air unit - Talon for GDI or Viper for Nod - you can trade against scarabs by simply doing a flyover. The scarab will set its own hex on fire, killing the other one as well.
You can actually make the scarab player kill their own units this way - if they ever have a scarab next to another ground unit, if you fly over the adjacent ground unit the scarab will blow them up as well.
Since scarabs are 30 and the cheap copters are 30, this is an even trade, but made better for you since scarabs are very slow to get into position while copters are fast. If you take the spot they were guarding with the scarabs you should be able to keep them from ever setting up there again.
