The purple or red tinged hairy shieldbug (Dolycoris baccarum) can be found throughout the summer on shrubs of the mainly of the rose family and that includes blackthorn or the sloe bush which gives it its other common name of the sloe shieldbug. They can be found from March right through until November but as they feed on both flowers in May and on fruits which are forming in August they tend to be more common at these times.
Shieldbugs are members of the sub-order heteroptera, and are 'bugs' in the true sense, hence the name hairy or sloe shieldbug. Shieldbugs are so aptly named with the body casing definitely resembling a shield. They come in all shapes and sizes, but always looking as though they are carrying a shield on their back.
This is one of the most common species of shieldbug but you do have to look for them to find them as they are often deep inside a hedgerow blackthorn.