You may kill them in the 3 ways:
Kicking(This will still hurt you since it's close combat)
The one way to kill one from a distance is Buddy bug!
But the sparks from the buddy bug with the toxic gas don't mix because they start exploding and it may cause Damage so keep a disance! Fire-breathing Ants, Sparks and fire can cause some Toxic gas to boom (Note: The Bang from Sparks, Toxic gas and Fire can also be deadly , Not only do they hurt you but the hurt the enemies around you)