Hi,
That does seem dry enough. I assume the whole top is mesh?
If the paper towel on the ground is dry it should be alright.
Yeah do not dip the flies, its enough if the flies eat it. Water the honey down sufficently, if you offer the honey pure the flies tend to get grimey as the high sugar concentration dehydrates them.
You can offer fruit juice too, or fresh slices of fruit. Or sweet baby-food.
Greetings Simon