Citronella is a type of plant that has a strong smell. It is often used to make oils and candles that can keep insects like mosquitoes away. Full definition
There are four types of citronella collars on the market today, which can be of assistance in canine behavior modification. (professorshouse.com)
Great list, I will only add the necessity (for me) of citronella candles. (loveofhome.net)
These devices range from water sprayers and collars with citronella sprays to audible alarms that activate each time the animal barks. (texaswestveterinarian.com)