Indigo
The closest colour to indigo that I could find for rainbow colours in my garden.  I think this is a Silver Y moth feeding on the verbena.
The other colours are; red (Geraniums)  orange (Black eyed Susan)  yellow (Potentilla)  green (Alchemilla)    blue (Nigella)
(Thankyou for the stars and hearts for my 6th blipbirthday, taking it to page 3 on the Popular pages)