2010 Florida Citrus Pest Management Guide: Citrus Root Weevils
Citrus root weevils represent a complex of species known to infest citrus trees and various alternate host plants in Florida. The most common species infesting citrus in order of greatest geographical distribution are the blue-green citrus root weevils, Pachnaeus litus and Pachnaeus opalus, the Diaprepes root weevil, Diaprepes abbreviatus, the little leaf notcher, Artipus floridanus, and the Fuller rose beetle, Asynonychus godmani. Other lesser species inhabit citrus on occasion.
All citrus root weevils have a similar life cycle. They have three immature stages: egg, larva, and pupa. Adult weevils emerge from the soil and lay eggs on host plants above ground, the larvae enter the soil to feed on roots, and the pupae and teneral adult stages are spent below ground. Adults emerge from the soil throughout the year. Peak emergence varies within species and by geographical region (ridge vs. coastal and interior flatwoods). Peak adult emergence for the blue-green root weevils and Fuller rose beetle is normally April and May. Diaprepes adult emergence from the soil peaks in late-May to early-July, while peak adult abundance on the tree canopy parallel adult emergence in May/June but can have a second peak in late-August to mid-October. The second peak is sporadic. Little leaf notcher has three generations per year. Although there is some overlap of generations, adults appear most abundant in a tree in April/May, July/August, and October/November. All adult weevils are attracted to the nonreflective silhouette of the citrus tree trunk. Little leaf notcher and Fuller rose beetle are flightless and must crawl up the trunk, other species will fly to the canopy.