Hello, First the treatment: You can put hydrocortisone cream on the wounds and nose for the itching. Also you can give Benadryl (diphenhydramine) the dose in milligrams is the same as the weight of the cat. So 8mgs for 8lbs. The childrens Benadryl liquid is 12.5mg for every teaspoon.
I would be cautious about putting Deet on the cats as this is toxic to them as well. You may want to try a flea preventative like Frontline plus, Comfortis, or Advantage from your vet as a mosquito repellent. Talk to your vet about availability. Thanks for your question
J Bache, DVM