Aphids suck plant juices and coat the leaves with sticky honeydew. Use sprays of rotenone, acephate, malathion or Sevin. A high pressure water spray from the hose may be used to dislodge the insects.
Hawthorn lace bug discolors the foliage and leaves black flecks on the undersides of leaves. Apply sprays of acephate.
Mites cause yellowish foliage, and heavy infestations form fine webbing.