They are not harmful to humans
Zora Daniel
No. Mayflies are adults after they hatch. All they do is mate and die.
Mayflies have mouths as nymphs to feed and grow, but as adults, they lack functional mouthparts because their sole purpose is to mate and lay eggs before they die soon after. The adult stage is focused on reproduction rather than feeding.
Yes. They should be able to stand up for at least one season. (300-400 miles?) As long as the soles don't show much wear or cause you any pain they are probably fine.
All Microbes are not harmful. All virus are harmful. Some bacteria are harmful
some are harmful but some are not harmful
more harmful, most harmful
lion are useful and harmful
No they are not harmful.
If you need help I recommend you type in the specific question you need help with
it is very harmful or harmful depending on your body
It is not harmful to animals but it can be harmful/fatal to children
The word "harmful" is an adjective.