44 
Psyche 
[Vol. 92 
choose one of the plants, most groups eating more S. albus or more 
P. breviflorus (Fig. 1). Of the 39 groups of hybrid larvae, chi-square 
analysis showed that nine groups of larvae significantly (p < .05) 
preferred P. breviflorus, five groups of larvae significantly preferred 
S. albus, and 25 groups of larvae showed no significant preference 
for either plant. As shown in Fig. 1, however, few of the groups ate 
equal amounts of both plant species. In virtually all of the choice 
tests the larvae clearly tasted both plant species, and thus were 
exercising a definite choice between the two discs. 
To compare the amount of variation in hybrid offspring within 
and between different females, I compared the amount of P. brevi- 
florus eaten as a percentage of the total amount eaten of both plant 
species. One-way Analysis of Variance using arcsin transformed 
percentages showed that there was more variation within the offsp- 
ring of a single female, than among the four females (Table 2). Thus 
there was no genetic variation in hostplant preference among the 
hybrid offspring of the four females. 
Discussion 
Larvae from the two populations of E. chalcedona and E. colon 
clearly showed a genetic preference for their own hostplant, while 
Table 2. A. Amount of Pensiemon breviflorus eaten by hybrid offspring as a 
percent of the total amount eaten of both plant species. Mean (S.D.) is given for each 
female. B. One-way analysis of variance comparing variation within the offspring 
of each female with that among individual females. Analysis performed with arcsin 
transformed data. 
A. 
Female # 
1 1 
12 
5 
2 
Percent P. breviflorus eaten 
33.92 (32.07) 
65.59 (28.45) 
56.72 (39.05) 
64.50(38.1 
Number of groups of 10 larvae 
6 
10 
18 
5 
B. 
Source of 
Degrees of 
Sum of 
Mean 
F 
P 
variation 
Freedom 
Squares 
Square 
Among families 
3 
1955.28 
651.76 
.87 
n.s. 
Within families 
35 
26093.54 
745.53 
Total 
38 
28048.81 
