The absorption of water by the eggs of Corixa punctata Illig. (Hemiptera-Corixidae) under experimental conditions.

Poisson (1924) states that the eggs of aquatic Hemiptera increase in volume as they develop. Kerenski (1930), Ludwig (1932), Evans (1933), Johnson (1937), Roonwal (1936), and Birch & Andrewartha (1942), all have described in various insects the changes which take place in the developing egg and which are generally associated with the absorption of water. The eggs of Corixidae are aquatic and are normally in contact with water throughout their life. Poisson regards salinity of the external medium as an important factor affecting the distribution of adult aquatic Hemiptera. Corixa punctata Illig. is a species which occurs normally in fresh water, but is sometimes found associated with typically euryhaline species in brackish water. It was thought that factors such as salinity and temperature, which might affect the uptake of water by the egg, might influence significantly the distribution of the species. Experiments were carried out, therefore, to investigate the changes in water uptake by the eggs of C. punctata under various conditions of temperature and salinity. The nomenclature adopted in this paper is that given by China (1943).