Laboratory studies were conducted on the role of flood on egg development, survival and hatchling weight in the solitary phase of Locusta migratoria migratorioides (Reiche and Fairmaire). Egg development is retarded by flood, particularly if the eggs develop for a long period in ordinary moist soil prior to flooding. Floods are also detrimental to egg survival; eggs that are flooded immediately after oviposition and those flooded when they are about to hatch are particularly susceptible. Egg age at flooding is a major determining factor of hatchling weight; heavier hatchlings are produced if eggs develop in ordinary moist soil for longer, rather than shorter, period before being flooded. Length of flooding period has no apparent effect on hatchling weight.