But the spray from 1 alien can mess up a few Arachnids, if close.
The xenos also have shown us that they dont mind sacrificing their own to weaponise this facet to their being.
A mentality seen in Alien Resurrection, Alien Vs Predator 1 (Maybe 2 too. I cant recall right now)...
The Xeno/Arachnid hybrids would also presumably start to replace fallen Xeno numbers as the battle progresses.... And the Xeno/Brain Bug hybrid would be awesome.
A terrifying small bus-sized vicious alien with two sets of jaws that could complete calculus that would make Stephen Hawking shit himself.