Insects are difficult to study because they represent the most species-rich, yet one of the least known, of all taxa of living organisms, a problem that is compounded by a scarcity of skilled entomologists (Anon, 2003). Although the number of described insect species is uncertain due to synonyms and lack of global list, most recognize 900,000-1,000,000 named morpho-species, representing 56% of all species known on Earth (Anon, 2003). Sensible estimates of the number of insects yet to be discovered range from 1 million to 30 million species (Erwin, 1991), although most predict around 2-8 million more species (May, 1990; Gaston, 1991; Odegaard, 2000). Approximately 100,000 species of insects have been described from sub-Saharan Africa, but there are very few overviews of the fauna as a whole (Miller and Rogo, 2001). It has been estimated that the African insects make up about 10-20% of the global insect species richness, (Gaston and Hudson, 1994) and about 15% of new species descriptions come from Afro tropical region (Gaston, 1991).
The order Lepidoptera may have more species than earlier thought and is among the most widespread and widely recognized insect orders in the world. Linnaeus (1758) recognized three divisions of the Lepidoptera, i.e., Papilio, Sphinx and Phalaena, with seven subgroups in Phalaena. These persist today as 46 super families of Lepidoptera with an estimated 174,250 species (Mallet, 2007), belonging to 126 families. Butterflies (superfamily papiliniondae) are estimated to comprise approximately 10% (Capinera, 2008). However, this figure is contentious because of the continuous addition of new butterflies and due to ongoing disagreements between taxonomists over the status of many species.