The creation of a distinct subspecies on the strength of a few less cornuti in the male aedeagus is not warranted, especially as the genitalia within the Smerinthini are naturally somewhat variable. This requires further study. Likewise, the transverse lines can be either very prominent, or totally absent, while the hindwing patches may be any shade of red or brown, and any size. Gynandromorphs are common, and if each half is a different colour, the effect can be striking. Developing pupae subjected to heat produce pale buff to rose-red adults.
Cold conditions can produce adults which are dark grey.
The region's commonest hawkmoth, and one of the most widespread. Frequents almost any damp, low-lying area, such as country lanes, open woodland rides, railway cuttings or town parks, particularly where Populus spp. Up to 1600m in the Alps. Most emerge late at night or early in the morning, clambering up the tree trunk at the base of which the larva had pupated. Not until the following evening does the moth take flight, females quickly selecting a resting position amongst foliage from which the males are attracted at around midnight.