304. Johnson's Jumper

 Phidippus johnsoni is the largest jumping spider that we have seen on Leaning Oaks and is one of the largest on the west coast.  The teal chelicerae are particularly striking.

P. johnsoni is the most common jumping spiders in the west, its range extending from northern Mexico, east to the Great Plains and north to southern Canada. Despite that, there are others that we have seen here more frequently. They feed mainly on flies, other spiders and will eat aphids (yay!) . ​

The tubular silken nests are located under rocks or wood are two to three times greater than the length of the spider's body.  They remain in the nests at night, copulate in the nests and will remain in a nest for approximately two days pre-molt and six days post molt. They will use the same nest for up to 33 days (Jackson 1979). If you are looking up anything on the biology of Johnson's Jumping Spiders or Red-backed Spiders as they are known in some places, you will run into Robert Jackson's papers from the late '70s an early '80s; someone with keen observational skills and natural history interest. At least for this species!

These are both females at different molts. The males are solid red, whereas the females have the black stripe up the middles with varying amounts of design. The female on the right has had fewer molts than that on the left. They may have six to eight molts, males will have seven to nine (Jackson 1978). These both were found at the same time within a metre of each other so I am curious if siblings will molt at different rates. 

Jackson, R. R. 1979. Nests of Phidippus johnsoni (Araneae : Salticidae) : Characteristics, pattern o f occupation, and function . J . Arachnol . 7 :47-58 . 

Jackson, R. R. 1978 . The life history of Phidippus johnsoni (Araneae : Saltiicidae). J. Arachnol. 6 :1-29