With all his fineness of scent, the dog is incapable of such feats as are realised by the moth, which is embarrassed neither by distance nor the absence of a trail.
It is admitted that odour, such as affects our olfactory sense, consists of molecules emanating from the body whose odour is perceived.

The odorous material becomes diffused through the air to which it communicates its agreeable or disagreeable aroma.

Odour and taste are to a certain extent the same; in both there is contact between the material particles causing the impression and the sensitive papillae affected by the impression.
That the Serpent Arum should elaborate a powerful essence which impregnates the atmosphere and makes it noisome is perfectly simple and comprehensible.

Thus the Dermestes and Saprinidae, those lovers of corpse-like odours, are warned by molecular diffusion.

In the same way the putrid frog emits and disseminates around it atoms of putrescence which travel to a considerable distance and so attract and delight the Necrophorus, the carrion-beetle.
But in the case of the Great Peacock or the Oak Eggar, what molecules are actually disengaged?
None, according to our sense of smell.