MOTHY STARRY NAVIGATION

We know that there are various means by which birds navigate long distances, but what about insects, many of which migrate? The bogong moth Agrotis infusa (Boisduval, 1832) which is in the same genus as, and looks rather like, our heat & dart (A. exclamationis), is an Australian species that migrates more than 1000km to aestivate in cool caves in the Australian Alps. A paper in Nature[1] describes how researchers discovered that these moths, which are nocturnal, when tethered and placed in an artificial setting under an image of the night sky and after disabling the magnetic field sensing which these moths also have, use the stars to navigate. By rotating the image of the stars above the moths in the experiment, the scientists could change the direction of their flight. This is reported as the first time an insect species has been shown to use the stars to find their way. 

In the UK, we have many migrant moths and perhaps some of them use the stars, too, although most scientific sources point to the wind as the main vehicle by which they move long distances.

The silver Y moth Autographa gamma (Linnaeus, 1758) is a famous and familiar migrant to Britain, often occurring in large numbers[2], but there are many others, among them one which you may have seen in an English garden in recent summers: the spectacular hummingbird hawk-moth (below), but this is a diurnal species so won’t be using the stars on its journey from southern Europe and North Africa.

 

Other moths that migrate in large numbers to Britain include:

bordered straw Heliothis peltigera

convolvulus hawk-moth Agrius convolvuli

the gem Nycterosea obstipata

jasmine moth Palpita vitrealis

pearly underwing Peridroma saucia

Rannoch looper Itame brunneata

scarce bordered straw Helicoverpa armigera

small mottled willow Spodoptera exigua

the vestal Rhodometra sacraria

white-speck Mythimna unipuncta

and a good many others, but whether any of them use the stars is not known. 

At Betts Ecology I run moth surveys using an ultraviolet light to attract them so they can be recorded, and we manage our sites to optimise habitat for moths and other insects that enrich the biodiversity status of the local ecosystem.

[1] DOI: 10.1038/s41586-025-09135-3

[2] Many years ago, my school participated in a project to determine if these moths picked up radioactivity from Sahara dust in their long journey from North Africa to the UK. They did. The radioactivity arose from residues after Cold War bomb tests.