THE COMPARATIVE UTILIZATION OF 
CULTIVATED AND WEEDY UMBELLIFER SPECIES 
BY LARVAE OF THE BLACK 
SWALLOWTAIL BUTTERFLY, PAPILIO POLYXENES 
By James M. Erickson 1 
Dept, of Entomology, Cornell University, Ithaca, New York 14850 
Introduction 
For many years, much of the emphasis in agriculture and plant 
breeding has been placed on increasing overall production (Allard 
i960). This is because man is almost totally dependent on plants 
tfor his food. The things he eats come directly from plants or in- 
directly from herbivorous animals. Plants are also the major source, 
directly or indirectly, of most clothing, fuel, drugs, and construction 
materials. 
The impact of insects on plants cannot be overemphasized. For 
example, some insects can be very successful in the biological control 
of weeds (Holloway 1964). Insects also have a great impact on the 
evolution and ecology of plants through their destruction of seeds, 
young seedlings, or the plants themselves (Breedlove and Ehrlich 
1968, Janzen 1969, 1971). The relationships between the insect 
and the plants that we observe today are based upon millions of years 
of co-evolution. During the course of this evolution, plants have 
developed various mechanisms to resist insect attack. The majority 
of plant defenses can be classified as physical or chemical defenses 
(Stahl 1888). Plant physical defenses may include thickened cuticle 
(Tan ton 1962, Feeny 1970) or hairs, spines, and thorns on the epi- 
dermis (Johnson 1953, Pearson 1958, Bernays and Chapman 1970), 
which interfere with the insects feeding. The high silica content of 
some plants or the crystalline materials in the leaves of many conifer 
species add a further physical barrier to insect attack (Merz 1959, 
Pathak 1969). 
Plants have also evolved a great array of chemical defenses, the 
so-called secondary substances. These include the alkaloids, glyco- 
sides, tannins, flavenoids, terpenoids, essential oils, and saponins, to 
name a few (Fraenkel 1969, Whittaker and Feeny 1971). Stahl 
(1888) advanced the idea that these compounds evolved in plants as 
1 Present address: Dept, of Biological Science, California State Univer- 
sity, Hayward, California 94542. 
Manuscript received by the editor May 20, 1975. 
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