Unless you can freeze dry them there is no benefit in drying them out. Just wash them under tap water and then put them in small plastic containers (ice cube containers work best). Freeze them solid and then put the frozen blocks into a ziplock bag and keep it in the freezer.
If your freezer has an auto-defrost cycle (most new fridge/ freezers do), put the frozen larvae into an icecream bucket that is packed with ice and keep the lid on it. This will help insulate the frozen larvae and stop them thawing out and refreezing each night during the defrost cycle.
And all fish go nuts over mozzie larvae. It is one of the best foods for any small fish. They are also easy to get and are clean. If anyone has containers of water sitting under trees in their backyard, check them regularly for mozzie larvae and use them as food. You will be helping control mosquito populations in your area and giving your fish something that will get them all excited.