Moved from Madrone Psyllid .

This one has been bothering me for a while now. My first question: what would a Madrone-specialist that has never been recorded on another host be doing on Ceanothus? If an isolated instance, I wouldn't give it a second thought; adult psyllids are found all the time on plants other than their hosts. What gave me pause was Alice Abela's psyllid (which I maintain is the same as yours) also on Ceanothus, as well as your nymph on Ceanothus, nymphs being much more host-restricted than adults:

I consulted the relevant literature (Schwarz 1904, Crawford 1914, Ferris & Hyatt 1923, Tuthill 1943) and I've come to the conclusion that this is most definitely not Neophyllura arbuti. Despite the obvious color differences (the species is described as reddish-brown to yellowish-brown with light brown wings, and dark maculae ahead of the clavus), there are marked differences in wing venation and head structure. Perhaps the most pronounced difference is in the venation:

Note the heavily sinuate veins, especially Rs and the branches of M, the small size of the cubital cell, and the complete absence of a pterostigma, none of which agree with your psyllid. Additionally, the head structures don't match Schwarz's description either, notably the shape of the genal cones, the insertion of the antennae, and the antenna length, which are described as being smaller than the width of the head. I did a quick overlay of Schwarz's head diagram with Alice's photo to demonstrate the inconsistencies of head shape in a way which may be more easy to understand than a text description: here.

Hopefully these factors prove how this psyllid cannot be the same as the one in your photo (if you're interested, I've uploaded 3 descriptions and 2 images of N. arbuti here if you wish to compare them as well; this comment would be too long if I went over everything). But if not N. arbuti, what is it? More psyllid species occur on Ceanothus in California than any other plant. However, after reviewing the literature for all relevant species and running through the relevant keys, I've come to the conclusion that it is Euglyptoneura robusta, and there isn't really anything similar to it.

E. robusta's description fits your psyllid perfectly: general color variable,but head and thorax usually light brown, and white forewings with 2 large dark irregular maculae. The overall white color is caused by a fine white pulverulence covering more or less the entire insect. The structure of the head is also consistent (another overlay with Crawford's illustration superimposed on Alice's image is here - note the position of the antennae insertion, the shape of the genal cones and vertex (the direction the antennae are pointing - more forward in Alice's image - is obviously not important). The wing venation is also much more consistent:

Note the large cubital, the short non-sinuate M and Rs veins, and the small pterostigma. Note that Crawford's original illustration was very faded such that the maculae were very faint, I adjusted the contrast in photoshop to better show these, but as a result they became somewhat blurred. Blurriness aside, note the position of these maculae relative to your psyllid. Also note the antennae length, over 1.5x the head width. All other visible characters and structures also agree with the species' description, which I've uploaded here if you're interested.

After doing all of this research, I was surprised to find that E. robusta already exists in the guide in the form of this pinned specimen:

Note that the extent of the brown maculae is variable in this species according to both Tuthill and Crawford, but despite their reduced appearance in that individual they are still positioned in the same manner as your images when they are preasent. Structurally, your psyllid is also consistent with that pinned specimen (though they are so much prettier in life than while dead, I must say).

I propose both your psyllid and Alice's psyllid be moved to E. robusta. I also propose that your nymph be moved to 'Psyllidae' - I can't say with certainty if it corresponds to this species, or to this other psyllid you found on the same Ceanothus:

or if it's one of California's other 10+ Ceanothus psyllids. Unfortunately, the life history is not known for many of them.

his comment: "This is a native species formerly in the genus Euphyllurus. This color form is rather unusual but this is probably the right species name. It feeds on Arbutus menziesii (Madrone)"

Moved from Euphyllurinae.

Moved from Psyllidae.

Yes Psyllidae, they look to be in the genus Euphyllura or near by. I'm not sure on species. We get several of these pretty little guys here in the Sierran foothills.