Starscream snarls wordlessly, too preoccupied by the dead signal he's getting back to strike back with any sort of suitably witty banter. He is also increasingly aware of the hole that he's dug himself here by threatening Airachnid and then not having any of the muscle to back it up. Probably better to cut and run.

So, without any warning, he looses a shot at her to cover his ass while he transforms and tries to fly off.