What brings MTS out of hiding?

[LancsRick]

I've had a few MTS knocking around in my tank for a fair few months, nice to have some hitchhikers that are welcome for a change. Having not seen them for months, they're back in force tonight and a couple are over an inch in length. Is there anything in particular that brings them out, or have they just been doing a subterranean tour of my substrate for the last few months?

 

[Henry]

They tend to learn the light pattern. More often than not, they will start to emerge just minutes before lights out. Put an algae wafer or something in a jar overnight. You'll find it's teeming with them hours later.