Abstract:
We demonstrated allometric differences in re lative head mass in different
instars of 12 species of Satumiidae and 14 species of Sphingidae. The differences were
related to the different ways in which individuals from the two fami lies ate their respective
host plants and to the different properties of the hosts that tcnded to be favored by each
lepidopteran family,
The salurniids tcnded to have various simple cUlling methods, while the sphingids tore
and crushed the food, so that in the former, ingested food was in the form of relatively
large uniformly sized pieces, and in the latter it was apparently well masticated. Satumiid
mandibles were short and simple, while sphingid mandibles were long, toothed, and ridged
in a variety of complex ways. The food ofsaturniids tended to consist of old, tough, tanninrich
leaves, while that ofsphingids was softer, younger, and contained small toxic molecules.
The generalists within each group tended to be similar to one another, while the specialists
(which occurred more frequcntly among the sphingids) had very characteristic mandibles,
each of unique design. One sphingid species feeding on a vine with characteristically very
tough leaves had the "satumiid" design of mandibles. The features typical of the two groups
of caterpillar are discusscd in relation to feeding strategy, digestion, avoidance of plant
" defenses," and rapidity of ingestion.
