As with other bluets, the Tule Bluet is distinguished from forktails by having lots of blue in the abdomen. This gives rise to the useful mnemonic:
lots of blue in it = bluet
The Tule Bluet is separated from other bluets by the almost equal-width bands of black and blue on the middle segments of the abdomen. This is the key field mark for this species. In many cases, Tule Bluets are numerous at a given location, even when no other bluets are seen. Perched Tule Bluets fold their wings like a tent over the abdomen.
Here's another view:
Tule Bluets are often numerous in the vegetation along the shore of a lake or pond. They are frequently seen flying in tandem. Females use their ovipositor to cut a slit in a stem of vegetation and deposit eggs inside. Sometimes, the tandem pair lands on a stem emerging from the water, and descends on it until the female is completely submerged. The male stays attached and goes underwater with the female in some cases, but more often releases his grip when partly submerged, and hovers until the female reemerges.
It is not uncommon to see a female in the bushes with the abdomen of a male still attached to her thorax. This strange situation occurs as the result of an attack by a darner, who grabs a tandem pair and snips off the thorax of the male for a snack, dropping the rest into the bushes. Here's an example: