Ticks are blood-sucking parasites of many kinds of animals. Both males and females feed on blood. The basic life cycle of a tick is egg, six-legged larvae, eight-legged nymph, eight-legged adult. Many California ticks have a single instar (the stage of ticks between successive molts – the first instar being the stage between hatching of the egg and the first molt of the immature tick) during the nymph stage.

Female ticks can produce thousands of eggs.

California has 50 different known species of ticks. These ticks can be classified into two large groups (known as families) based on certain obvious anatomical features. These two families are the Argassidae (soft bodied ticks) and the Ixodidae (hard bodied ticks). Soft bodied ticks lack a hard dorsal shield and visible mouth parts when viewed from the top, while hard bodied ticks have these features. California has 19 species of soft bodied ticks and 31 species of hard bodied ticks. Napa County has 10 confirmed species of ticks, two soft bodied and eight hard bodied.

Some species of ticks are host specific while others will feed on any available animal host. Hard bodied ticks usually remain attached to the host for a few days to weeks, feeding slowly on host blood and tissue fluids. Soft bodied ticks usually feed quickly and tend not to remain attached to their hosts for long periods of time. An exception is the Pajahuello Tick which can remain attached for up to nine days.

Hard bodied tick habitat may vary because of their lengthy feeding period and the mobility of their hosts. Soft bodied ticks tend to live and stay within the host’s nest.