Recent studies by Bünzli (1935) have demonstrated the importance of ants of the genus Acropyga (subgenus Rhizomyrma) to the cultivation of coffee in Surinam. The ants (Rhizomyrma paramaribensis Borgmeier and R. rutgersi Bünzli) tend coccids on the roots of the Liberian coffee trees and these coccids transmit an infectious phloëmnecrosis. This phloëmnecrosis in epidemic years caused a loss of 20–40 per cent of the coffee production in many fields in Surinam (Stahel, in Bünzli, p. 559). Earlier studies by GÖldi (1892), Pickel (1927) and Costa Lima (1928) showed that coccids (Rhizoecus coffeae Laing) tended by other species of this subgenus caused severe injury to coffee trees in northeast Brazil. According to Donisthorpe (1936) a species of Rhizomyrma has recently been taken associated with a coccid at the roots of coffee in Colombia.