This week we noticed some major pest infestations on pyracantha bushes around campus. The most noticeable is woolly apple aphid infestations. These produce cottony fluff along the branches. When you brush away the fluff (really it is wax the aphids produce) you will see hundreds of pink or grey aphids crawling around. Woolly apple aphids have been out for a month or so now but are becoming very noticeable now. Infestations for multiple years produce large leafless patches on bushes. The aphids cause galls to form on branches and branches become black from sooty mold. Soap or oil should provide some control but other aphid management information is here.
The other pyracantha pest that just started hatching is hawthorn lacebug. The major
landscape plants that hawthorn lacebugs feed on are pyracantha, service berry, and cotoneaster. Lacebugs management information is here. Imidacloprid will kill both pests but should not be used on plants that are flowering or that will flower soon due to negative effects on pollinators.
Another bug that pyracanthat seems to be ‘infested’ with are lady beetles. These are predators and attracted by aphids and lacebugs but I have found pyracantha bushes with dozens of larvae and pupae on them.