Flea Repellent with Essential Oils of Flowers & Plants

We had been using a mixture of the essential oils of lemongrass and eucalyptus along with water in a spray bottle. The proportions are 5 drops of eucalyptus and 4 drops of lemongrass in approximately 4-5 cups of water. It had been working very well on our dog, but we had some problems with our spray bottle and went about 2 weeks without regular applications. On the last visit to the vet, we had her checked and she was without fleas. 3 weeks later, we found fleas in the doggy bath. This was following the lapse in regular spraying. At this point we will attempt to decontaminate and try to determine if the spray is no longer working, or it was from a lapse in diligent spraying. There are many different sources of natural and homeopathic flea repellents from various sources, and unfortunately there doesn't seem to be a standard. This book has some great information and is written by a Vet: Hound Health Handbook by Dr. Betsy Brevitz.