After my mosquito fear mongering a few days ago I decided to make a few pairs of play pants for my son (otherwise know as a human mosquito magnet).
I make these pants from up-cycled men's dress shirts I find at thrift shops. A men's size large is usually big enough for a full length pair of kid's size 2T or 3T pants. The material is light weight, still fairly durable, highly washable, and cheap. Best of all, my kid's think they are comfy, and the elastic waistband is easy for them to take on and off for potty breaks.