I've been researching some homemade formulas for use against the bad bugs. I've not tried most of them. If you are allergic to any of the ingredients, please do not use. Always test in a small place first.
Original formula Listerine (the yellow stuff) in a spray bottle would repel mosquitoes (Dave's Gardens). Broadcast spraying in an outdoor area seems to cause the pests to vacate the premises. (One has to assume this is temporary and used for gatherings and guests) I've no idea if it also leaves the entire yard smelling like a dentist office.
Use garlic cloves in an open rain barrel and it may work for a week or two to keep larvae down. This idea was highly debated on the net - it works vs. it doesn't work. There are recipes for boiling garlic and spraying on plants - guaranteed to smell up your house for the day.
American beauty berry plant, Callicarpa americana, may have potential as a natural insect repellent. Research is being done on making it into a lotion but scattering crushed leaves from the plant among animal bedding may be effective. The FDA has not approved it in lotion form.
One place claimed catnip is 10 times as effective in repelling mosquitoes as deet. Catnip also works for roaches and apparently termites too! Lemon balm, and marigold are promising plants for repelling certain species of mosquitoes. If you see someone who has planted marigolds around their garden, it is with the hope the smell will repel crawling insects.
Dragonflies eat flying adult mosquitoes, and the dragonfly nymphs eat the mosquito larvae.
Absorbine Jr. rubbed on the skin will fend off gnats. (Jeff Lampe of the Peoria Journal Star)
Chimney swifts can eat 1200 mosquitoes a night - a third of their weight in insects every day. Build a chimney-like structure where Chimney Swifts can roost and nest. Should you want to do this project, let me know - I have the plans.
Bats in our area typically eat night flying insects like mosquitoes and moths. They live in trees, attics (not the best) and bat houses. I also have plans for bat houses or you can buy them from NAGS and other sources. Street lights and farm nite lites attract the night flying insects which in turn attract bats. Do not kill bats - 30% of our bats are endangered in the US. Do not play with bats because they are afraid of you. You do not want them to bite you even though less then 1/2 of 1% have rabies. Let them go about cleaning up the 600 bugs they eat an hour.
Toads and frogs eat insects, slugs, grubs, crickets and worms (most any crawling or fluttering insect). They will not eat dead insects.
Birds eat insects because they need protein to grow in readiness of migration, to molt, and to fly. All birds eat insects at times in their lives especially the young. Dead trees attract insects which in turn attract over 85 types of birds to Illinois.
Skunks and lizards also eat insects - good luck on that one.
Cedar oil spray (get at places like PetSmart) may be an insect repellent for animals & humans.
Rubbing alcohol rubbed on the skin and let to dry may repel mosquitoes.
Vicks Vaporub rubbed on pants and legs is said to repel ticks. It may stains on clothes.
Avon Skin-So-Soft oil mixed half-and-half with rubbing alcohol and rubbed on the skin. This hint was from a Marine who had to camp out a lot.
A spray of half real clear pure vanilla and half water. This is the vanilla you get in Mexico or health food stores.
Plant garlic next to or around rose bushes.
Lavender oil put on pulse points (wrists, ankles, knees, ears, where skin folds.)
It appears most herbal oils have been used at one time or other as a repellent on the skin. Make totally sure you are not sensitive by testing first. Oils can be pretty strong.
I use Dr. Bronner's Liquid Castle peppermint natural soap (available at Uncle Billy's health food store, Target or on Amazon.com) to wash the dogs. It keeps flies and other pesky bugs away for about a month. It is safe for humans and clothing if you would like to give it a try (see image). It comes in other "scents" which may work for you. (Picture of Dr. Bronner's from their web page)
These are a few of the hundreds of possibilities - hope it's just in time to help you this summer "bug" season.
"I dreamed I was a butterfly, flitting around the sky; then I awoke. Now I wonder: Am I am man who dreamt of being a butterfly, or am I a butterfly dreaming of being a man?" Chuang Tsu