The recent sweltering weather seems to have encouraged a population explosion of these little pollen beetles Meligethes aeneus, seen here infesting Rosa gallica versicolor. The last time we had this many in the garden was back in 2010.
These little beetles are attracted to anything yellow and feed on pollen. Their larvae feed on oilseed rape - so there is a vast food supply for them in spring and early summer, when they eat the flower buds then pupate in the soil,with the adults emerging about a month later and moving on to wild flowers and cultivated plants in gardens. They overwinter as adults in the soil and re-emerge in spring, feeding on pollen of early spring flowers like lesser celandine while they wait for the oilseed rape crop to flower.
Pollen beetle feeding on a dill Anethum graveolens flower.