As stated by the devs:
You cannot study the first attack of a particular kind using a Combat Instruction, which, instead, must still be learned from an animal. If you have a Combat Instruction in your Study Report, however, you will -- this specifically for the first attack of that kind -- always receive the attack in question from any animal which gives it, removing the random chance to get that particular attack. Should a Combat Instruction thus help you to get the first attack of a particular kind, it will be consumed at no cost in LP.
As i understand it:
If i have a combat instruction for take aim in my study inventory and i do not have any instance of take aim in my deck, i should receive take aim from the first animal that can grant take aim. As it seems, this does not work for me killing ants.
The wiki might just be mistaken and ants are not able to yield this attack.