Egg distribution and survivorship in the pierid butterfly, Colias alexandra

Patterns of egg distribution and survivorship were examined for six generations (1975-79 and 1981) of a univoltine population of the pierid butterfly Colias alexandra. Unlike some other of the so-called red-egged pierids, there is no evidence of egg-recognition in this Coliadine species. Two distribution patterns were observed: contagious or clumped in 1976-1979, but random in 1981. Generation to generation, survivorship to diapause of clumped individuals relative to all individuals shows no consistent pattern. Among clumped individuals, survivorship is two times greater for the first or previously-laid individual than the second or subsequently-laid individual, suggesting that if there is a genetic basis for the common contagious pattern, selection is acting against it. The importance of obtaining data which reveals inter-year variation in assessing or interpreting egg distribution is discussed.