1975] 
Erickson — Papilio polyxenes 
1 15 
a great deal of biomass in a short time, the respective consumption 
indices may in fact be identical. 
A more useful index for the growth rates of an individual larva 
is the mean dry weight added to larval biomass per day. This 
measure gives the investigator a much more accurate estimation as 
to the growth potential of the various umbellifer food plants. 
For the purposes of food utilization and efficiency determinations, 
the experiment was concluded when the larvae molted into the ulti- 
mate instar. The larvae were then reared through to the adult stage 
on the same experimental plants that they fed upon before and dur- 
ing the utilization experiments. All resulting adult females were 
then utilized in various host plant selection experiments. 
The data are generally presented as a mean and standard error for 
the larvae in any particular host plant treatment group. The various 
experimental parameters were subjected to one way analysis of vari- 
ance (Guenther 1965, Snedecor and Cochran 1967) to determine 
differences among the various treatment groups. A typical T-test for 
2 independent samples of unequal sizes utilizing a pooled variance 
(Guenther 1965) was used for analysis of the differences between 
cultivated and wild umbellifer species. Linear regression analyses 
were performed and the significance of the correlation coefficients 
was tested using a table of critical V values (Snedecor and Cochran 
1967) . All statistical procedures were completed with the aid of a 
programable calculator (Olivetti programa 101 or microcomputer 
P602). 
Results 
Various plant parameters differed greatly between cultivated (do- 
mesticated) and wild (weedy) species of Umbelliferae offered to the 
swallowtail larvae (Table 1). The dry matter content of the leaf 
material was significantly lower (P < 0.0 1) at a mean of approx- 
imately 12.25% for the cultivated umbellifers than the wild umbel- 
lifer species which had a mean of about 21% dry matter. In terms 
of caloric content, no significant difference (P < .3) was found 
between the cultivated species, at a mean of about 4.11 cal/mg dry 
weight, and the wildly occurring species, at a mean of about 4.13 
cal/mg dry weight. The nitrogen content of the leaf material was 
significantly higher (P < 0.05) in the cultivated species, averaging 
approximately 1% higher than the wild species in terms of total 
nitrogen. This value becomes significant when converted to protein 
content, as 1% nitrogen equals approximately 6.25% protein (Lord 
1968) . 
