How can I tell if my pet has fleas? A flea-allergic dog's reaction to fleas can usually be noticed as hair loss at the lower back, above the tail. A flea-allergic cat's reaction will usually be noticed as hair loss and bumps around the neck and head. In most cases - the owner will see small (sand- grain size) fleas moving through the pet's fur. The male fleas may be black to brown in color, while females may have an enlarged orange abdomen. In other cases adult fleas may be difficult to observe on the pet, but the reddish-black flea feces may be apparent. To confirm that these are flea feces, the animal should be brushed in a manner that allows the feces to land on a white, moist cloth such as a handkerchief. If these are indeed flea feces, they will dissolve leaving blood – red marks that can be seen on the cloth. These are flea droppings left by the fleas. http://www.myfleatrap.com/FAQ.asp