After a little research I find the entire world, save for the UK, call/spell the particular moth as "Gypsy Moth", the UK being the only English speaking nation to spell it as "Gipsy Moth". Trust the Brits to be the odd man out, but one has to ask why? Days of Empire superiority? Ref page 12 common names.
https://www.fs.fed.us/foresthealth/t...antria_web.pdf
Brits have now fallen into line.
https://www.forestresearch.gov.uk/to...es/gypsy-moth/