&middotDrought damage - needles gradually turn yellowish-green and then light brown. This starts at the top of the tree and progresses downward and from the outside in. &middotAnimal injury - dog urine can cause some browning and dropping of lower branches on arborvitae and junipers.
There are many different brands of cat flea collars. Generally, flea collars work by either emitting a toxic gas to the local area (head/neck of the pet) or by exuding chemicals that are absorbed into the animal's skin. Some flea collars have an Insect Growth Regulator (IGR), to prevent development of cat fleas, eggs and larvae.
Update 4: My cats do go out but they spend a fair amount of time in the house. Update 5: Thank you for your good wishes Kirin Kat and my good wishes back to you and your cat. My vet doesn't recommend flea collars and I use a treatment called Stronghold which treats some types of worms as well as fleas.nce a month. If you are worried about the chemicals look for a flea bath that is designed for sensitive skin. The chemicals are not harmful for you kitty. It's the chemicals keeping fleas with yucky diseases away from your lovely animal.