Experiments were done to analyse the process generating spatial distribution pattern of the eggs laid by two species of bean ■evils, C. chinensis L., and C. rhodesianus Pic. (species name of the latter is not yet determined by taxonomist). The experiments were conducted under the the condition of 30℃ 75% R. H. and 16hr. illumination. The cage used for the experiment was 64×64cm in size and less than 1cm in height. In the cage 64 beans were scattered evenly or in clumps, (Fig. 1). ■ chinensis, the value of I_δ. an index showing the spacial distribution pattern of the eggs, the number of eggs oviposited, and the number of eggs per bean increased with the increase of the number of females released. In C. rhodesianus, too, the number of eggs deposited and the number of oviposited beans increased. In this species, however, the I_δvalue and the number of eggs per bean remained unchanged with the increase of number of females released (Table 1). In C. chinensis, the number of oviposited beans changed with the variation in bean distribution. In. C. rhodesianus, the number of eggs per bean and the value of I_δ changed. How ver, in C. chinensis, the number of eggs per bean and the value of I_δ did not change with the variation in bean distribution. In C. rhodesianus, the number of oviposited beans remained unchanged. In both species, the number of eggs oviposited showed no significant difference statistically with the variation in bean distribution though in C. chinensis, the averages were 76.7 in uniform distribution and 52.8 in clumped distribution (Table 2). In C. chinensis, and adult female had a strong tendency to avoid the beans already oviposited and to look for fresh beans for her oviposition, this bringing about the oviposition of a rather uniform distribution of eggs over the area. C. rhodesianus female was less discriminative and her eggs were laid randomly on beans within a limited area so that the eggs tended to be distributed in clumped pattern. It was observed that the female of C. chinensis walked round a bean in a large circle
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