Neem is a rather amazing oil, not as well known as it should be considering its usefulness. With excellent moisturizing qualities, it is becoming increasingly popular in many body and hair care and pet products. Neem oil contains compounds that have both insecticidal, antiseptic and medicinal properties. It is a dark, rather sludgy green in color and has a strong, (not terribly pleasant) odor. Being both high in Vitamin E and fatty acids, Neem oil is said to be useful for treating a variety of skin problems such as eczema, psoriasis, acne and dry skin. In addition, Neem has a long history of use as an insect repellent and is increasingly being used to control plant pests and diseases. Neem oil has been studied and shown to be effective against mosquitos, flies, sand fleas, ticks and more. As a garden spray, Neem (which is very bitter in taste) makes the leaves sprayed with it distasteful for the bugs to eat, thus acting as a natural repellent.
For external use only. Note that Neem oil is thick, and can solidify at low temperatures. If that happens, place container of oil in warm (not hot) water and heat gently.

Neem Flea and Tick Repellent

10 drops cedarwood atlas
6 drops lavender
3 drops rose geranium
1/2 Tb Neem Oil
1 Tb olive or soybean oil

Add to 1 pint water and shake well. Place mixture in a spray bottle and use as extra protection before walks, outdoor exposure etc. We started using this in combination with the more traditional flea treatments when those quit working effectively, and so far it seems to be helping.