In order to not encounter these when flying over swamp use bug repellent or fly high enough to where the demon bugs won’t load in. Killing one is also very easy, get a journeyman or better crossbow and keep shooting at it until it uses its ranged attacks, dodge the attacks ( or lead it to a paracer and to distract it), and keep shooting at it while it’s close to the ground to kill it. Killed around 50 of these wretched beasts this way :]