A YEAR'S EXPERIENCE WITH THE COTTONY CUSHION SCALE IN PUERTO RICO

Abstract

1. The Cottony Cushion, or Fluted Scale of Australia, Icerya purchasi Maskell, is known to have been present on rosebushes in Puerto Rico since early in 1931, and presumably had been present for some time previously. 2. It first appeared in noticeable and destructive abundance on casuarinas (Australian pines) in San Juan and Santurce, and in citrus groves mostly less than ten miles to the west and southwest of San Juan, during the exceptionally dry spring of 1932. 3. Natural dispersion of the scale is by the pre vailing north-east winds: from the original focus in San Juan and Santurce to the west and southwest. 4. In the citrus groves well protected by windbr eaks, the scale was entirely eliminated by an entomogenous fungus, Spicaria javanica, never before recorded from Puerto Rico, which attacked it during the extremely wet weather of May 1932, and persisted during tile following humid summer months. 5. The Australian lady beetle, Rodolia (Novius) cardinalis Mulsant, brought to Puerto Rico by airplane from Florida and later from New Orleans, is reasonably efficient in cleaning up scale infestations in less humid locations, such as exposed citrus groves, and on casuarinas growing close to the ocean or planted to serve as windbreaks. 6. Of native parasites, the most important is a Phorid fly, Syneura cocciphila Coquillet, originally described from Mexico, and never before found in Puerto Rico. The scale is also attacked by a wasp, Cheiloneurus pulvinariae Dozier, described from Puerto Rico, and by a small lady-beetle, Decadiomus pictus Chapin, a new and previously undescribed species. 7. During dry weather, almost perfect control is obtained by spraying with a standard heavy engine oil-fish oil soap emulsion, of which fusel oil is the stabilizer. 8. Except in special instances where especially well protected by high buildings, all the large scales and practically all the small scales were carried away and destroyed by the hurricane of San Ciprián, September 26-27, 1932. A few scales in protected locations on their hosts escaped destruction and were later able to increase rapidly in abundance because the hurricane had been even more destructive of their natural enemies. 9. So far as can be determined, the hurricane had no effect in the dispersion of the scale.