Morphological descriptions on immature stages of Porisaccus jiuhuaensis(Wu) and the origin of bag-like appendage(Homoptera:Pseudococcidae)

In this paper, three immature stages of Porisaccus jiuhuaensis (Wu) were described and illustrated firstly and then, discussion on the origin of bag-like appendage on ventral surface of adult female showed that this bag-like appendage was vestige of the metathoracic legs based on degeneration of legs and absence of oval pore plate from the 1st instar nymph to adult female.