Mothron is indeed a tough opponent, as it is the strongest mob of the entire solar eclipse event.
Something is to be taken in consideration once this mob has spawns : the more you are distant from him, the more it is likely for him to use his super-fast charging attack. So don't try to completely outrun it.
Using low range Melee weapons isn't recommended, your highest priority is to have a constant spacing for having better chances of dodging his attacks, and the most effective way of improving your dodging abilities is to use ... wings.
Here is one thing that can be very useful about this boss :
Sometimes, Mothron slows down, lands, and lay an egg, while being a static target for a couple of seconds. Using a weapon that hit multiple times (the death scythe in your screeshot, for example) at this moment is nice, as it will damage Mothron a lot and the egg that will spawn under it. To force him to land, prioritize your attacks on any Mothron child/egg you see.
In a crimson world, it is always good to inflict the ichor debuff on every ennemy you fight, maybe it won't work on Mothron, but it will make the others mobs of the solar eclipse less of a bother. Equip ichor arrows, ichor bullets and drink an ichor flask (made from an imbuing potion). This may require some farming in underground crismon biomes, but it is well worth the effort.
Also, transform the terrain at your advantage beforehand, make an arena if you haven't already.
A good arena is an arena that helps a player move swiftly, and helps regain health : campfire, heart lantern, honey spot, heart statue, sunflowers, etc...
For movement : place platforms in a large grid pattern. This way, you would have better way of quickly changing your movement speed without using wings.