Robertson, C.M., & de Villiers, E.A. 1986 Parasites of avocado pest bite the dust.. Citrus and Subtropical Fruit Journal No. 632: 7.

Notes: According to C.M. Robertson, Protopulvinaria pyriformis can increase in numbers on avocado trees in South Africa where dust is not controlled. Dust disturbed by vehicles drifted onto trees and hindered natural enemies such as parasitic Hymenoptera. According to E.A. de Villiers, the following natural enemies of the scale have been identified in South Africa: the encyrtid parasites Metaphycus galbus, M. stanleyi and M. helvolus; the aphelinid parasites Coccophagus basalis and C. pulvinariae; the eulophid parasite Tetrastichus sp., the hyperparasites Cheiloneurus cyanonotus and Marietta javensis; and the predacious coccinellids Hyperaspis sp. and Chilocorus angolensis.