Other caterpillars will starve to death rather than even try to adapt to a new diet.
But there is a logical reason behind this strategy:
Many plants contain ingredients harmful to caterpillars, like ethereal oils in cruciferae. large white butterfly caterpillar on brassicaceae leaves In the course of evolution caterpillars have adapted to feeding on these plants by detoxifying their harmful substances.
This very mechanism is based in part on a particular enzyme system,
with which toxic substances can be metabolized in a way, to be eliminated easily.
midgut epithelium cells, the arrow marks the columnar cells
The enzymes are located in the mid gut, in a special celltype called columnar cells.
The arrow on the picture above marks these cells

For my doctors thesis, I'm examining these detoxification enzymes on differences
in various Austrian caterpillar species.
gypsy moth caterpillar at 2nd larvae instar
I am working on establishing a bio-monitoring system
which shall be based on the various abilities of their detoxification system
to metabolize anthropogenous pollutants as well.

During the last few decades, Austrian butterfly population drifted
without relevant alteration of their habitats or nourishment resources.
Variations in their enzyme equipment may explain this population drift.

© Onview.net Ltd, Microscopy-UK, and all contributors 1995 onwards. All rights reserved. Main site is at www.microscopy-uk.org.uk with full mirror at www.microscopy-uk.net.