1 12 
Psyche 
[March 
species: io species of cultivated umbellifer and 22 species of wild or 
weedy umbellifers found in the Central New York area. The larvae 
were maintained on these species throughout larval development. 
Mature and uninjured leaves of the wild species were gathered in the 
field each day and the leaves of the cultivated umbellifers were col- 
lected from greenhouse reared plants. All leaves were sealed in 
plastic bags and offered to the larvae within 2 hours. Leaves were 
replaced and feces collected every 24 hours to prevent bacterial or 
fungal development. The larvae were reared in clear plastic boxes 
(9 X 12 X 4 inches) (Tri-State Plastic Molding Co., Henderson, 
Ky.), in a climatically controlled chamber with the following para- 
meters: temperature 22° day, 18 0 night, approximately 55% hu- 
midity, and a 16-8 LD photoperiod. 
For the purposes of examining larval energy and nutrient utiliza- 
tion, a minimum of 8 and a maximum of 10 newly molted 4th instar 
larvae were placed individually in glass petri dishes (Pyrex, 100mm 
X 15mm) lined on the bottom with a piece of Whatman No. 1 
filter paper. The ideal utilization study would, of course, encompass 
the entire life cycle as the efficiency of food utilization by the early 
instars is certainly of interest. The nutritional adequacy of the food 
plant material can be judged only by its ability to support growth 
in successive instars. There were, however, 2 reasons for utilizing 
only 4th instar larvae in this experiment. Since larvae of P. polyx- 
enes consume approximately 0.1% of the total food ingested during 
larval development during the 1st instar, these minute quantities of 
food ingested and digested lead to exceptionally high error values and 
are therefore inaccurate. Similar results were obtained for the 2nd 
and 3rd instars where the percentage of the total food consumed 
during larval development was 0.6% (L2) and 2.8% (L3). The 
ultimate instar was not included for the purposes of the energy 
utilization experiments due to a pre-pupal clearing of the gut in 
which a larva may lose up to 40% of his maximum wet weight 
within a 5 minute period. Once this occurs, there is no way to 
estimate the maximum larval weight which is necessary for various 
calculations to determine larval food utilization efficiencies. During 
the 4th instar, approximately 10 to 15% of the total food ingested 
during larval development is consumed. These larger amounts lead 
to more accurate weights which significantly reduce the statistical 
error. 
All the individual larvae were placed in the same controlled tem- 
perature room, except for the period of time each day during which 
new food was offered to the larvae and the feces collected. The 
