Praying mantids (Insecta: Dictyoptera, Mantodea) attracted to light at a savanna site in Ghana (Legon) were studied over 34 months. 1771 insects of 26 species were recorded, most of which were males. There was a gradual decline in numbers during the study, which was probably due to habitat deterioration. Significantly more mantids were attracted to light on new moon nights than when the moon was full. For the second commonest species, Sphodromantis lineola, a significant correlation was found between mantid numbers and rainfall per month. Some species appear to have two peaks of abundance per year, others only one, while the commonest species, Miomantis paykullii, shows no clear seasonal pattern, but longer term studies are required to confirm these tentative conclusions.
Three measures of diversity are calculated and compared with mantid data from elsewhere in the tropics. Diversity at Legon was found to be very similar to that at Lamto, Côte d'lvoire, despite different methods of collecting the insects, but the mantid fauna of Panama is less diverse than at the two African sites. Suggestions to account for this result are presented.