Two old tricks from a professional I used to know.

One is the 'floating candle' trick - does work - the more the better.

The other is 'the thumper'. Vibrations such as footsteps etc triger the dormant eggs to hatch. You can build a small 'thumper' device.

These two work well in combination.

Warning - if you wish to also use 'flea bombs' make sure all the candles are extinguished - the carrier gas CAN catch fire/explode.