Much to my surprise, my record of Alder Leaf Beetle (Agelastica alni) was the SEWBReC (South East Wales Biodiversity Records Centre) record of the week for week ending 12 July. I had thought these beetles were common so was a little surprised to read in SEWBReC’s social media post that ‘It is expanding its range, so any records help track its spread.’ So, I took a look at the NBN Atlas map, which shows there are few records so far in south Wales, and I also checked the UK Beetles website, which notes

It was formerly considered extinct in the UK; it was recorded a few times from widely scattered localities across England during the mid-20th century but following its rediscovery in 2004 in northwest England it has spread rapidly and it is now locally common and often abundant across the south of England and the midlands and it seems to be increasing in range and abundance.

As well as several of the shiny blue adult beetles, my leaf-bothering had turned up lots of larvae. The UK Beetles website also gives interesting details about these tiny creatures:

females oviposit during May and June …attach groups of eggs to the underside of host foliage, usually between 50 and 70 eggs in each batch and each will lay between 200 and 250 … Larvae emerge 10-12 days later, they pass through 3 instars and are fully grown within 25-30 days; they feed communally but in the last instar disperse throughout the host plant, they are very distinctive and easily recognized; elongate and pale grey when small and shiny black as final instars.