I've been making our own insect repellant, which is much needed in southern Georgia, the mosquitos are already out in force! I've been using it on our DS since he was about 4 months old.
2oz carrier oil (anything you want, olive will stay on your skin forever but feels really oily, something like grapeseed will sink in and not feel so strange but doesn't seem to last as long because of it...but we do spend hours and hours outside each day amongst hordes of mosquitos)
30 drops citronella eo
20 drops cedarwood eo
15 drops basil eo
10 drops lavender eo
10 drops rosemary eo
(you can use whatever oils you wish, but all of these are baby and pet safe...I'd say the big ones to use would be citronella and basil if you had to choose)
These oils are known to help with mosquitos but personally I'd avoid pennyroyal, eucalyptus, clove, nutmeg and cinnamon with those 3 and under and pets or those known to be sensitive to things like cinnamon, etc.:
pennyroyal, lemon balm (citronella), thyme, and lavender. Other choices include bergamot, cajeput, eucalyptus, rose geranium (this works for ticks, too), myrrh, peppermint, rosemary, oil of clove, oil of nutmeg, feverfew, cinnamon stick, and mint.
Just apply everywhere and you're good to go! I don't put it on the underside of DS's hands or ends of his fingers that might go in his mouth and don't put it around his eyes, but will slather his forehead and cheeks and he does great with it.
This one I found somewhere but haven't tried yet.....
Better Basic Sunblock Formula
2 1/2 ounces sesame oil
1 1/2 ounces of cocoa butter
1/2 ounce beeswax
4 ounces distilled water
2 tablespoons zinc oxide (available from herbalists or the pharmacy; you may also substitute titanium dioxide for zinc oxide, since it has similar properties)
25 drops grapefruit seed extract (as a preservative; available in health food stores)
Melt the oils and beeswax in a double-boiler over medium heat. Remove from the heat, add the water, and mix with an electric handheld mixer until thick and creamy. Add the zinc oxide and preservatives. Makes 1 cup.
Preparation Time: 30 minutes
Shelf Life: 6 months
Storage: Glass jar with screw top