|Small insect peppers this Senna with small balls of solid sugar.|
Gevork got back to me the the next day. He pretty much nailed it. It was a Caesalpinza psyllid, a small sucking insect that apparently causes little or no damage to its host. here is the description he sent me:
CAESALPINZA PSYLLID, Freysuila dugesii, -(Q)-This psyllid is one of several in the genus that feed on leguminous shrubs and trees in Caesalpinia and Poinciana. The first California record comes from Palm Desert, Riverside County, where it was collected on a golf course by County Ag Biologist Richard Shaffer in January. The host was Caesalpinia cacalaco. This small shrublike plant with yellow and orange flowers is being commonly planted these days in many southern California and Arizona locations. Our specimens were confirmed by Dr. Ian Hodkinson in England. Little is known about this psyllid as it has been collected only sparingly over the years. It is most likely native to Mexico, the native home of the host. No apparent injury such as galling or malformations to the plants were noted. It is likely restricted to these hosts and whether it will cause damage to them in the future in ornamental plantings is unknown.
This also makes sense because Senna wislezini is closely related to the host, Caesalpinia cacalaco. It might infest Mexican Bird of Paradise plants (Caesalpinia pulcherrima), but if it did it would probably not damage the plants. So thankfully this pest is probably nothing to worry about, but I'll keep an eye on it. Interestingly the coating of sticky solid honeydew balls could be a manner of camouflage for the pest, making it tough for birds to discern the sticky sugar balls from the psyllid.