Spittlebugs or Froghoppers are small, plant sap-sucking bugs in the family Cercopidae. Adult Spittlebugs look like Leafhoppers and like them are good jumpers. Spittlebug nymphs (immatures) are sedentary and rarely seen. If you spot what appears to be a white, foamy glob of spit in a bush, it is most likely hiding a Spittlebug nymph. Here in the Sonoran Desert, Spittlebugs can be seen on various desert herbs and subshrubs, especially those in the Aster Family (Asteraceae).
Spittlebug nymphs use the spit blobs to hide and protect themselves from predators like birds, other insects, and spiders. The spit blobs also help them keep cool and moist in the desert heat. If you wipe away the spittle, you'll find a nymph like this little brown-headed one below clinging to the stem.
The "spittle" produced by a Spittlebug nymph is something far more disgusting than spit, it's actually fluid expelled from a Spittlebug's anus mixed and frothed together with a mucilaginous (moist and sticky) substance secreted by its skin glands. Because they suck watery plant sap all day, Spittlebug nymphs have plenty of anal fluid to use for spit blob making.
I discovered these dripping spit blobs above not long after a summer monsoon thunderstorm, so I assume that the clear drops are rainwater instead of excess anal fluid (yuck).