[2] They are moderate to large in size and are distinguished among moths for their agile and sustained flying ability, similar enough to that of hummingbirds as to be reliably mistaken for them.

This hovering capability is only known to have evolved four times in nectar feeders: in hummingbirds, certain bats, hoverflies, and these sphingids[3] (an example of convergent evolution).

For example, in the African species Agrius convolvuli (the convolvulus or morning glory hawk-moth), males have thicker antennae and more mottled wing markings than females.

[6] A number of species are known to be migratory, all in the Sphingini and Macroglossinae, and specially in the genera Agrius, Cephonodes, Macroglossum, Hippotion and Theretra.

The relative magnitude of the two frequency responses enables the moth to distinguish rotation around the different principal axes, allowing for rapid course control during aerial maneuvers.

[5] Usually, their bodies lack any hairs or tubercules, but most species have a "horn" at the posterior end,[2] which may be reduced to a button, or absent, in the final instar.

Tobacco hornworms (Manduca sexta) detoxify and rapidly excrete nicotine, as do several other related sphinx moths in the subfamilies Sphinginae and Macroglossinae, but members of the Smerinthinae that were tested are susceptible.

However, other species, such as Hyles euphorbiae and Daphnis nerii, do sequester toxins from their hosts, but do not pass them on to the adult stage.

[5] Night-flying sphingids tend to prefer pale flowers with long corolla tubes and a sweet odor, a pollination syndrome known as "sphingophily".

The comet orchid (Angraecum sesquipedale), a rare Malagasy flower with its nectar stored at the bottom of a 30-centimetre-long (12 in) tube, was described in 1822 by Louis-Marie Aubert du Petit-Thouars, and later, Charles Darwin famously predicted there must be some specialized moth to feed from it: [A. sesquipetale has] nectaries 11 and a half inches long [29 cm], with only the lower inch and a half [4 cm] filled with very sweet nectar [...] it is, however, surprising, that any insect should be able to reach the nectar: our English sphinxes have probosces as long as their bodies, but in Madagascar, there must be moths with probosces capable of extension to a length of between 10 and 12 inches!

The Madagascan individuals had a pink, rather than white, breast and abdomen and a black apical line on the forewing, broader than in mainland specimens.

Molecular clock models using either rate- or fossil-based calibrations imply that the Madagascan subspecies X. m. praedicta and the African subspecies X. m. morgani diverged 7.4 ± 2.8 Mya (million years ago), which overlaps the divergence of A. sesquipedale from its sister, A. sororium, namely 7.5 ± 5.2 Mya.

[17] Since both these orchids have extremely long spurs, longspurs likely existed before that and were exploited by long-tongued moths similar to Xanthopan morganii praedicta.

The long geological separation of subspecies morgani and praedicta matches their morphological differences in the color of the breast and abdomen.