Meat-eating, ground-nesting yellowjackets have plagued man in summer and early fall throughout California and in many other states. Although yellow-jackets seldom become a problem in heavily urbanized areas, there are often large populations of these wasps in foothill and mountainous localities. Yellow-jacket nests are particularly common in parks, campgrounds, and foothill residential areas. Attendance at many public and private recreational facilities has been sharply reduced because of the menace and attack of yellowjackets. There are great variations in the severity of these pests from year to year, but yellow-jackets are responsible for many stings each year. Hypersensitive reactions to their venom are quite common and have resulted in death. Even the normal degree of reaction to multiple stings can be severe enough to require hospitalization.