Dictionary.net

• A jumping plant louse of the family Psyllidae, of many species. That of the pear tree is Psylla pyri.

2010 - New Age Dictionary Database
By Oddity Software

• A jumping plant louse of the family Psyllidae, of many species. That of the pear tree is Psylla pyri.

1913 - Webster's Revised Unabridged Dictionary
By Noah Webster.