The capability of Phormidium animalis, a cyanobacterium commonly found in larval habitatsof Anopheles albimanus in southern Mexico, to support larval development of this mosquito was investigated.First-stage larvae were reared under insectary conditions wilh P. animalis ad libitum and their development wascompared with larvae fed with wheat germ. The time of pupation and adult mosquito size, assessed by winglength, were similar in both groups, but fewer adult mosquitoes were obtained from larvae fed with the cyanobacteria.Nevertheless, these observations indicate that P. animalls is ingested and assimilated by larval An.albimanus, making this cyanobacterium a good candidate for genetic engineering for the introduction of mosquitocidaltoxins for malaria control in the region.