Small White v Female Orange Tip

[caveman38]

Only 2 years into butterfly spotting. I can't believe (although no photos) that I saw 7 species / types / varieties - what do you guys say?
I live in a busy London borough and have a wonderful nature reserve / conservation a small distance away. I saw Orange Tips, Small Whites / I believe a Large White, Comma, Peacocks (many), Holly blue (I think maybe a common) & a solitary Speckled Wood.
I confess to not being able to instantly tell the difference between female OT and Small Whites. Any quick fire tips, please.

[Padfield]

Hi Caveman. If you catch a glimpse of the underside of the butterfly, there is no risk of confusion between female orange tips and any of the common whites. The female orange tip has a very distinctive marbled green pattern. If you don't see the underside and just get a quick view of the upperside, notice that the forewings of the female orange tip look very rounded. This is partly because they are more rounded than those of the other whites, and partly because of the shape of the dark apical patch, which accentuates the roundedness. Of course, there are differences in the pattern that you can learn by looking at the pictures, but this roundedness is a useful part of the 'jizz', allowing for quick separation in the field.

Flight and behaviour are also rather different, but these are best learnt by experience, after first making sure you can identify them formally.

Guy

[David M]

Along with what Guy has said above, another thing to look for is what they are settling on. Female Orange Tips are absolutely obsessed with cuckoo-flower (which is their main larval host plant). That's not to say Small/Green Veined Whites don't nectar from it too; they do, but far less frequently than Orange Tips. It's almost as if this plant has a magnetic 'pull' on OTs.

[caveman38]

Thanks guys
"the forewings of the female orange tip look very rounded" is the thing that I feel will be the most noticeable for me. I'll put it to practice on my daily (allowed) walk tomorrow.
All this beautiful weather we're having around London has at least brought plenty out. Shame I can't visit the South Downs, where I'd be every 3 weeks but for the lock down.
Any of you guys know what I'm missing?