Are getting badly chewed up by mosquitos. I don't know what to do. There's no point putting any thing on them either before or after because he will just lick it off.
Crush some tansy or neem leaves and rub it around the area - the odour should persist enough to give some relief from the mossies Cider vinegar will help stop the itching after biting - I believe it has some antiseptic properties, too - may help stop the bites becoming infected
If the cat will wear a collar, make a collar of cotton rope and add drops of some of the following essential oils onto it, or if you have the plant itself, beat some of the leaves into the cotton of the rope (remove cat first). The effects are said to last about a week, then fades. Thai lemon grass, eucalyptus, citronella, lemon balm, garlic, geranium, lavender, thyme, spearmint or peppermint essential oil. Herbology Organic Mosquito Repellent is made in New Zealand with 100% pure organic evening primrose oil with citronella and geranium essential oils. Sue
Please don't use essential oils on cats, it's dangerous. It probably also messes with cats' sense of smell (which is highly developed). https://www.thelavendercat.com/