The development of hypotonic inflation, air-drying techniques
for obtaining insect chromosomes by Crozier (1968) and the
subsequent use of Giemsa stain on such preparations by Angus
(1982) paved the way for far clearer chromosome preparations to
be obtained. Angus (1982) initially used developing eggs of Helophorus
species (Coleoptera: Helophoridae) as his source of mitotic
chromosomes, and this suggested the application of the techniques
to Callosobruchus eggs, readily obtained from cultured material.