Of the four common ticks found in Contra Costa County, only the Western black-legged tick (Ixodes pacificus) is capable of transmitting Lyme disease. Adult females are about 1/8 of an inch long and are reddish-brown in color, while males are slightly smaller and are brownish-black in color.

The District provides identification of ticks and biting or stinging pest insects submitted by Contra Costa County residents. Contra Costa County Residents may bring in or mail a tick or pest sample to the District (place tick or insect in a plastic baggie, then in an envelope and mail to the District. Note: we only accept actual insects for identification. Please do not bring in or submit other material to the District. 

The District does not test ticks for Lyme disease that are brought in by the public. Lyme disease testing is conducted for surveillance purposes only. A list of local laboratories that will conduct Lyme disease testing on ticks can be found by clicking here.