[Harj]

Hi, I am a new member and hope someone can offer me some advice and/or guidance.
We have noticed (what look like) beetles in our kitchen and bathroom. I don't believe they are cockroaches - they have small antennae and black bodies. I have searched the Internet to get an idea of which specific type but haven't really been 100% successful. I have also noticed that they come in 3 sizes! Large - approx 4-5cm, medium 2-3cm and small 1-2cm. They tend to come out at night and when confronted - scurry off underneath the washing machine or something. Even the cat doesn't know what to do with them.
Can anybody please help with an insect-friendly solution (ideally) that will re-locate them or any other suggestions?? I have been advised about ultrsonic products and then told they are useless by someone else?!?

Thanks in advance,
Harj