Gleditisa tricanthos ‘Sunburst’ is one of the preferred hosts of honeylocust plant bug

Honeylocust Plant Bug nymphs were found feeding on emerging foliage of Gleditsia tricanthos (honeylocust) in the Greater Toronto area this week.  Plant bugs are tiny, yellow-green insects that feed with piercing-sucking mouthparts on emerging foliage.  They have a toxic saliva and tissue around the feeding sites will often become distorted and brown.  Premature defoliation will occur, but usually is minor.  The bigger issue seems to be tiny plant bugs falling off trees and onto lawn furniture and/or people.  Hold the honeylocust foliage up to the sky and look for shadows of tiny, tube-shaped bugs resting on the upper leaf surfaces.  DOUBLE-CLICK PHOTOS to enlarge them.

Now do some counts, where you are finding more than 5-7 per compound leaf…..

…..the populations may warrant an insecticide spray to try and reduce leaf injury.  Insecticidal soap is an great alternative for managing this pest in the landscape.  Dormant oil applied to bark just before bud burst will help reduce successful emergence of overwintering eggs.  Although it is more of a pest in landscapes, honeylocust plant bug can occasionally be found in the nursery.