Occasionally you see a wild Blackberry bush with leaves that have stunted growth and are often curled up. This malformation is due to the Blackberry Psyllid (Trioza tripunctata), also known as the Jumping Plant Louse. Closely related to aphids and scale insects, psyllids are plant-feeding bugs which typically have one specific host on which they feed and lay their eggs. Blackberry Psyllids, small, cicada-like insects that hold their wings tent-like over their body, feed only on Blackberry and in so doing, cause this leaf distortion.
Blackberry Psyllids have one generation per year. The adults mate and lay eggs (39-202) on Blackberry bushes in early summer. The nymphs, small and wingless, also feed on the sap of Blackberries. They are often found inside the curled leaves during the summer months where they secrete several types of waxy structures as they feed. In the fall the nymphs mature and overwinter as adults in conifers (pines, spruces and cedars) prior to returning to Blackberry bushes in the spring. If Blackberries are one mile or more from conifers, no psyllid damage will be found; those growing within one-eighth of a mile from conifers are at the greatest risk of psyllid damage.
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