psylla vs psyllid

psylla and psyllid both are nouns.

Word	Noun	Adjective	Verb	Adverb
psylla	Yes	No	No	No
psyllid	Yes	No	No	No

As nouns, psylla and psyllid are synonyms defined as:

psylla and psyllid: small active cicada-like insect with hind legs adapted for leaping; feeds on plant juices

Other synonyms of psylla include jumping plant louse.

psylla (noun)	psyllid (noun)
small active cicada-like insect with hind legs adapted for leaping; feeds on plant juices	small active cicada-like insect with hind legs adapted for leaping; feeds on plant juices