Yes, I think that it only works on live fleas, not the eggs. The melaleuca oil also works on ticks. You just have to put a drop of it on the tick and it will usually back right out....sometimes you might need 2 drops. Also, to prevent fleas and ticks you can make a solution 10:1 of water and T36-C5 melaleuca oil and put it on your pets coat after it has been washed. This keeps the coat shiny and beautiful and prevents the fleas and ticks.