Anyone who has spent much time around plants will be familiar with this classic gardener’s pest, the aphid. Aphids use their piercing-sucking mouthparts (a characteristic of the order Hemiptera) to drink the fluids of plants. Fluid uptake occurs passively via the pressure generated by the plant’s own circulatory system. In fact, the aphid’s mouthparts actually contain valves to limit the flow. Without such systems the aphid would literally be blown off the plant. It is more the equivalent of attempting to drink from a firehose than sucking from a straw.
Aphids are gregarious insects which live in small subsocial colonies on plants. Reproduction varies among aphid species and may be sexual or asexual. Many aphid species give live birth to young. In the picture above and below, a few white and shriveled cast off exoskeletons are visible from developing aphids. These skins, called exuvia, can become quite numerous as colonies grow and become crowded. Overcrowding on plants generally triggers the production of winged aphids, which disperse to new host plants where they found new colonies.