There is always a moment in the early evening where you will have a visitation from every bug within a 5 mile radius. I have found that it is best to be well prepared for this onslaught. Some hatches might come with a screen that can be installed; others have homemade screens to put in place.   Place your screens on your hatches and openings before the bugs arrive. If you are going ashore in the late afternoon then put these in place before you leave the boat.  

Regular screen is often too coarse for the “no see ums” so we recommend a fine mesh.  I think it is called wedding veil mesh.  We have found a product that is a bug net with fine mesh and weighted edges.  Check out: https://sogeman.com/ . It can be draped over your deck hatches and there is also one for companionways.    Putting your screens on before the sun sets is a great way to continue to enjoy the evening.   Having a good fly swatter and some bug spray is essential too.  

There are a few places on the river that seem to harbour more than their fair share of horse flies.   Jemseg river is one of them.  They are nicknamed “toe flies” for a reason as they have a very stinging bite and love to feast on your feet. We recommend wearing white gym socks when going through the Jemseg it seems to keep the “toe flies” away.  Having a few artificial dragon flys pinned to your cockpit area helps as well.   You can often find these in the checkout aisle at Home Hardware.