www.ukbutterflies.co.uk

"Traditionally (recently) in the UK, I thought Large White Butterflies had been more numerous in the summer than in the Spring.
Eggs laid on host plants are in clusters and repeated laying by different females results in small and large caterpillars growing together that might eventually "devastate" a cabbage patch for human consumption resulting in immature caterpillars needing to move elsewhere. Some people's ideas stopped, with a fearful thought of wasp grubs that ate a caterpillar alive from the inside out.
What birds specifically, were encouraged the most, into one's cabbage patch in a garden to eat Large White Caterpillars full of wasp grubs?

Q2. Once one's Nasturtiums had got caterpillars, might it be a good idea to put one nasturtium filled hanging basket, in a less obvious position, (for example, not on a buddleja) , for another Large White Female not to find ?"

Q3. In Lincolnshire last year (2016), approximately mid-October was the last time I saw Cabbage Whites (Small & Large) in flight. Bearing that in mind, in that year, what might have been the best date for a Large Cabbage White to lay eggs for a successful 2017 Spring emergence ?
(I thought some Adult Large Whites came from Europe in the late Spring, males possibly travelling further than females, to find a mate).

Others on UKB have far better scientific knowledge than me, but it seems spring and autumn Large Cabbage Whites suffer far lower parasite rates than those in summer. Also, at least when I live, Large whites seem to have a slightly quicker life cycle than Small Whites, and more or less disappear in August, now we are in September they are common again. Whereas Small Whites don't have this August gap, so any third generation adults, if there are any, merge with second brood adults.

Nasturtiums, by the way, are not hardy and will be killed by the first frost. So any eggs laid on them now will not survive, unless the frost is very late.

Pieris Brassicae in Lincolnshire, United Kingdom 2019,2020
“This species had three broods a year in Lincolnshire (Egg hatching about late May, July and September). Those brooded in about September, overwintered as pupae and emerged March-May as less common adult butterflies (previously, possibly incorrectly, known as a Spring brood).
A brood definition was: "produced at one hatching, or birth"
(In butterfly life cycle sense, without confusion, that might have meant from egg, rather than emergence from pupa).
Pieris brassicae that overwintered as pupae, did not all emerge at once, depending on specifically located, micro-climatic pupa temperatures. Studies showed that a final instar caterpillar, preferred a “warmer” surface to pupate on (one that was not a fast heat conductor).

It was thought that migrant Pieris Brassicae did not reach the UK until general air temperatures were at least ?ºC, suitable for long distance flight.

Kind Regards