[Boy, does she wish she did.
What kind of nickname does one give to an antlion?]

Maybe a nickname that plays on what he actually is in your world? Something clever or cute.

[Maybe not cute.]

This might be a little obvious, but maybe something like 'Fang?' He can sound strong, if he wants to seem intimidating. [But even she's not impressed with that option. The gears in her head are turning as she tries to think of something more clever.]