F. B. Browne 
361 
In order to test the fecundity of individuals 1 placed in separate cells five 
freshly emerged females which had mated, supplying each with a resting 
Odynerus larva and, at intervals, removing from the latter the eggs and larvae, 
keeping a record of the totals for each female. In this way I found that the 
egg-laying capacity of the females varied considerably, the total number of 
eggs laid by each being: 961, 529, 1217, 1086 and 598. It will be noted however 
that the lowest total exceeds considerably the figures given by previous 
observers. 
The eggs and larvae were removed and counted, usually at intervals of 
seven days after the first few weeks, and at the end of six or seven weeks the 
females had almost ceased to lay eggs. The few eggs laid by each at this period 
were placed upon fresh hosts and allowed to hatch out in order that pupae 
might be obtained to determine the sex. They all proved to be males, indicating 
that the mother had come to the end of her supply of spermatozoa. A male 
was therefore introduced into each of the cells containing the females and, 
during the following week, the number of eggs laid in four out of the five 
cases ran into three figures. 
Although the number of individuals experimented with is too small to 
justify any definite statement, these experiments seem to indicate that the 
female normally lays about half her eggs after her first mating, the totals 
being 439, 270, 680, 348 and 597 and, in three out of the five examples, she 
had exhausted her egg-laying capacity after the results of a second mating, 
the numbers of eggs in the second broods being 522, 259, 333, 738 and 1 
respectively. 
The last few eggs of these second broods were allowed to hatch and the 
larvae reared in order to test their sex and, with the exception of a single 
individual, all were males, so that, at the same time as the female exhausted 
her supply of eggs she had exhausted her second supply of spermatozoa. 
The following table (p. 362) gives details of all the results referred to 
above: 
As to the rate of oviposition I have made no daily counts and at first 
I adopted a somewhat rough method of estimating which gave some very 
divergent results. Thus in August, in 17 days, out of a batch of four females 
the lowest yield was 152 eggs while one female gave 213 eggs. Of another 
batch of six females in the same month, one laid 92 eggs in 12 days while 
another laid 218 in the same period. These figures give averages per day of 
9, 12-5, 7-6 and 18-1. 
In December I began to go into this question more carefully, using the 
five females already referred to, and Table II shows the days upon which the 
counts of eggs were made and the average number of eggs laid per day as 
worked out from these counts. This table thus shows that the productivity 
of the female, when at her best, may reach 31 eggs per day and that she is 
at her best from 7 to 14 days after mating. I shall refer to the fecundity 
of the unfertilized female later on. 
