Planococcus citri vs mealy bug

Planococcus citri and mealy bug both are nouns.

Word	Noun	Adjective	Verb	Adverb
Planococcus citri	Yes	No	No	No
mealy bug	Yes	No	No	No

As nouns, mealy bug is a hypernym of Planococcus citri; that is, mealy bug is a word with a broader meaning than Planococcus citri:

Planococcus citri: feeds on a wide variety of cultivated plants but especially destructive to citrus
mealy bug: scalelike plant-eating insect coated with a powdery waxy secretion; destructive especially of fruit trees

Other hypernyms of Planococcus citri include mealybug.

Planococcus citri (noun)	mealy bug (noun)
feeds on a wide variety of cultivated plants but especially destructive to citrus	scalelike plant-eating insect coated with a powdery waxy secretion; destructive especially of fruit trees