A quick fix for mosquito bites is a chamomile tea bag dunked in hot water and cooled, then applied. Use the bag as a poultice.
I've never found a true means herbally to keep away mosquitoes. Some people say take garlic capsules. If you don't take blood thinners, you won't have a problem with garlic. But I'm just one of those people that mosquitoes love. I love garlic but mosquitoes love me more. =(