psyllid vs psylla

psyllid and psylla both are nouns.

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

As nouns, psyllid and psylla are synonyms defined as:

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

Other synonyms of psyllid include jumping plant louse.

psyllid (noun)	psylla (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