Note: This is a fun read – the author doesn’t hide her true feelings about ants! Wikipedia has this to say about camphor:
Pest deterrent and preservative
Camphor is believed to be toxic to insects and is thus sometimes used as a repellent. Camphor is used to make mothballs. Camphor crystals are sometimes used to prevent damage to insect collections by other small insects. It is kept in clothes used on special occasions and festivals, and also in cupboard corners as a cockroach repellent.
Camphor is also used as an antimicrobial substance. In embalming, camphor oil was one of the ingredients used by ancient Egyptians for mummification.
Solid camphor releases fumes that form a rust-preventative coating and is therefore stored in tool chests to protect tools against rust.
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Source: Practical American Cookery and Domestic Economy, E. Hall, 1856.