Aphid feeding on a corn leaf. The liquid droplets are honeydew excreted by the aphid during the digestion process. Because the honeydew is so rich in carbohydrates, many other insects find it a valuable source of energy. The sticky honeydew also supports the growth of mold that, in large amounts, can reduce the amount of light that reaches the leaf surface and, ultimately, photosynthetic capacity. check

HemipteraSternorrhynchaAphididaeaphidcornhoneydew