Hi Brooke. It is a pretty old letter, but I think the bites were sandflys. Not the gnat or noseeums type, but like the Australian one. My husband and I were told to look out for sandflys on the beaches in WA, but we did not see any flies, only a tiny tiny minute light brownish thing, we could only see because there were clouds of them.
In the evening we were covered in perfect circles, very red and about 1 cm in diameter. We were not worried as they did not itch....untill next day and the next 3 weeks. WE had more than 400 of these things which now looked like giant mosquito bites and itched 10 times more. We had to take antihistamines not to go crazy. Locals told us it was a sandfly and that it was not a bite but urine...I don't know if this is true. The upside is that they said to mix dettol and baby oil and rub it on your skin. This would prevent the bites or whatever it was. It did and was not as bad as the insect repellants you can buy.
Phatsoa