302 
Psyche 
[Vol. 89 
Table 1. Carapace width and duration of stadia in laboratory reared Heteropoda 
venatoria (L.). 
Instar 
Carapace 
width 
(mm) 
n 
S.D. 
Duration 
of stadium 
(days) 
n 
S.D. 
1st 
1.37 
10 
0.06 
11.80 
44 
1.56 
2nd 
1.69 
32 
0.08 
14.68 
40 
1.33 
3rd 
2.20 
27 
0.13 
26.32 
37 
5.28 
4th 
2.60 
22 
0.16 
27.97 
30 
4.21 
5th 
3.10 
41 
0.26 
28.52 
31 
5.67 
6th 
3.44 
38 
0.21 
36.11 
37 
5.41 
7th 
3.79 
39 
0.16 
36.42 
33 
6.60 
8th 
4.06 
39 
0.29 
44.46 
28 
10.56 
9th 
4.53 
43 
0.57 
40.69 
26 
16.63 
10th 
5.36 
43 
0.55 
35.48 
23 
12.57 
11th 
6.67 
33 
0.71 
28.11 
9 
6.57 
12th 
— 
— 
— 
23.0 
4 
7.83 
The mean carapace width for each instar (not separated by sex) is 
shown in Figure 1 to have a nearly linear relationship with the 
stadia, as might be expected. This and the large number of stadia 
seem to agree with a suggestion made by Hagstrum (1971) that large 
spiders have added stadia, rather than accelerated growth between 
successive molts. Sekiguchi (1945) shows similar data for the female 
of H. venatoria in Japan. The carapace widths for our spiders are 
summarized in Table 1. 
The ratio of females to males for reared spiders was 2.4/1 (22 
females/ 9 males). The sex ratio for adult specimens collected in 
Homestead, Dade Co., FL, on August 14-19, 1981 was 3.4/1 (71 
females/ 21 males). The sex ratio in Homestead might be due to 
cannibalism of the males by females, as mentioned previously. Of 
the females collected, 18.3% were carrying egg sacs, and all instars 
were observed to be present in the field. Summer seemed to be the 
major period of egg production both in the laboratory and in the 
field. 
This spider probably offers one of the best possibilities for the use 
of spiders in biological control as it is well adapted for living in close 
association with humans and is readily reared. As these spiders 
habitually feed on cockroaches, H. venatoria behavior and ecology 
may be an important key in the biological control of one of man- 
kind’s oldest pests. 
