Nymphal development and egg sac production of Xysticus bifidus Paik

Abstract

In rearings under a seminatural condition, the female of Xysticus bifidus Paik produced 2-3 egg sacs at intervals of about 1 month during her life lasted for 84.2 days on the average. The average of total egg number produced per female was 181.8. The 2nd instar nymphs, which emerged from 1st egg sac of a female during the period from June to early July, developed to abults in August and September under a seminatural condition. However, those which emerged from 2nd egg sac of the same female during the period from August to September overwintered at different instars including subadult, and developed to adults in April and May of the following year. From the above described results and other available information, it was considered that the field population of this spider consisted of 2 groups having biannual and annual life histories.