My kids get those too, but in their case its mosquito bites and ants.
What I do and works for them is:
1) I put "Bactine" spray on the bites, daily. (this helps the itching and healing and preventing infection) I personally apply it morning, afternoon, and before bed. And put a band-aid on it prior to when my kids go to bed at night.
2) I give them an ORAL antihistimine. Like Kids Claritin (does not cause drowsiness), or Bendaryl (which does cause drowsiness). But I mostly use Claritin.
Because bites cause itching, you need to give them an antihistimine. This helps stop itching and the ill effects of the bites, keeps the venom from spreading.
Watch for infection of the bites... but Bactine helps that.
My parents used Bactine on our bites, when we were kids too. I swear by Bactine. It comes in a spray or liquid form. I like the spray because its easier to apply on kids. It does NOT hurt or sting.
Hope this helps.
But of course, if the bites seem like it is getting infected, take him to the Doctor. Some kids are more allergic to insect bites.
All the best,
Susan