system
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human
How is dirt/debris/inorganic material handled or processed when a caterpillar passes through the pupal stage (and digests itself)?

Where I live (rural area) there are always lots of caterpillars seen near the fields and crossing roads this time of year. It is hot and the roads are oily and lots of tar/rock chip, etc. There have to be oil / tar / debris that sticks to the hairs of the caterpillars, and I was wondering how this stuff is accounted for when the caterpillar turns itself into soup inside the chrysalis. Do they shed an outer layer or dispatch of the hairs/fur before going through this process, to avoid complications? Could certain debris or chemicals cause issues during this transitional phase?
gpt
When a caterpillar transforms into a pupa, it is actually undergoing ecdysis (shedding its exoskeleton) for one final time. The new cuticle (in this case the pupal casing) is forming underneath the cuticle of the caterpillar during its final instar, and “transforming” into a pupa is just shedding its cuticle, allowing for all the debris/inorganic matter to be shed along with the former exoskeleton. As for the material inside the gut of the caterpillar, often times the larva stop eating before pupating and may purge their guts of undigested organic matter before pupating.