|The British summer, 2012|
In essence, it's because of what this picture shows: summer 2012 for most of the UK was a washout. It started raining about Easter and basically never really stopped. In general, rain is pretty bad news for insects;as cold-blooded animals wet, cold conditions stop them flying, which in turn prevents feeding, dispersing, breeding, and so on. Many insects, including several species of ladybird, are on the edge of their range in Britain, as far north as they can go before conditions get too cold, so damp, dark summers don't do them any favours!
That meant that the 2012 generation of ladybirds - the ones that would try to survive the winter and appear in spring 2013 - was very poor. Numbers were lower than normal, especially of species that lived mainly in trees (it's much harder to climb back up a tree than a small flower once you've been washed off it), and many of the individuals were smaller than normal, a sign of a lack of nutrition as a larva.
Once they emerge as adults in late summer, ladybirds have one job - to eat as much as possible to have the best possible chance of surviving six months asleep. Hamstrung by the lack of aphids to eat, it's likely that the majority went into the winter underweight, only to be faced by a winter that went on and on - personally I was still wearing two coats and a woolly hat for pollinator surveys into June! That meant that a lot of the ladybirds that went into dormancy last autumn simply ran out of energy and never woke up again, further lowering numbers. I spent almost every day in the field (well, in several fields) this spring, and only saw a ladybird on 29 occasions between New Year and the end of May, far fewer than normal. I did see several hundred Orange ladybirds (Halyzia sedecimguttata) at the Kings Weston BioBlitz in Bristol, but this is a mildew-feeding species at home in wet weather, and they were still in their overwintering aggregation in early May!
|A 7-spot ladybird larva (Coccinella septempunctata), snapped at dinnertime.|
If you see a ladybird, please do send us a picture record at the UK Ladybird Survey website or using the iRecord Ladybird app from CEH and Naturelocator (Android or Apple) - without records we have no idea what's going on anywhere else!