Last month’s arrest of two Florida girls whose relentless cyberbullying drove twelve-year-old Rebecca Sedwick to suicide has, for many parents, refreshed anxiety.

It also points to some glaring blind spots many of us non-teens have.

Sedwick’s mother’s, Tricia Norman, thought she knew what was happening in her daughter’s online world because she checked Rebecca’s phone texts and Facebook regularly. Unbeknownst to Norman, Rebecca had signed on to a number of other apps that allowed the bullying to continue under the radar.

For parents worried about being in the dark, here are four unfamiliar places where cyberbullies might lurk. If you see these apps on your child’s phone, get familiar with them: