Gnaturally

I am still waging terrible war on my fungus gnats.  The babies didn't at all like being immersed in alcohol hand gel but then I got lazy and they've only gone and bred like mad again.  This time I'm catching the adults who seem peculiarly drawn to a bowl of soapy water.  I tried an internet recipe of vinegar, sugar and washing up liquid, but it didn't do much, and just the washing up liquid seems to work better.  I've caught quite a few already.