Geograph - photograph every grid square

Nymphs of various ages and shed skins. These were part of a heavy infestation on thistles in Braidburn Valley Park. Some adults [black fly] have wings. Aphids are true bugs [Hemiptera] and feed by sucking sap from plants with piercing mouthparts. They can do a lot of damage, both directly and by transmitting viruses. In addition, as they are 'plumbed' into the plant's vascular system [phloem] which is under pressure, sugary fluids are secreted from the rear, which allows sooty moulds to develop on plants.