But the spider mite is impervious. One of its genes can make an enzyme that converts hydrogen cyanide into a harmless chemical. The same gene is present in the caterpillars of various butterflies and moths; they, too, shrug at cyanide. Neither the spider mite nor the caterpillars invented the cyanide-busting gene for themselves, nor did they inherit it from the common ancestor. The gene came from bacteria.34
