Aphids
curling leaves, and transmitting plant viruses. Some species of aphids are also known to excrete honeydew, a sticky, sugary substance that can attract other [...] cluster on the undersides of leaves, where they feed on plant sap. They may also be found on stems, buds, flowers and fruit. Damage: Aphids can cause damage [...] curling or distortion of the leaves, yellowing, or discoloration. They may also excrete a sugary substance called honeydew, which can attract other insects