Effects of water extracts of frass produced by A, B. Bombay locusts and C, D. Migratory locusts fed with rescue grass leaves on the numbers of egg pods laid (A, C) and holes dug (B, D) by adult female desert locusts presented with extracts mixed with sand. Two cups containing frass extract (treated) and water (control) were simultaneously presented to locusts in each of two locust cages, and the data were combined. Numbers in parentheses indicate the total numbers of days observed. Bars on histograms indicate one standard deviation. Asterisks indicate significant differences at the 5% level with a t-test. n.s. indicates no significant difference.