Butterfly Bush (Buddleia)
Plant Health Problems
This plant has no major disease problems in the Connecticut landscape.
Checker spot butterfly, Euphydryas chalcedone.
The large bluish-black caterpillars of this butterfly may feed on foliage. If needed, apply Bacillus thuringiensis var. kurstaki, which is among the compounds registered for control of this pest in Connecticut, when caterpillars are small. Consult the label for dosage rates and safety precautions.
Genista caterpillar, Uresiphita reversalis.
This pest is not usually a problem.
Japanese beetle, Popillia japonica.
Adults may attack this plant if other preferred hosts are not present. This beetle in the adult stage feeds upon a great variety of trees and plants. The beetle is about ½" long, bright, shining green, with copper colored wingcovers. Two white spots on the tip of the abdomen show beyond the ends of the wing covers, and there are five white spots formed by patches of white hairs on each side of the abdomen. The beetles begin to emerge the latter part of June but their greatest abundance is usually about the middle of July. During drought periods, populations of Japanese beetle are drastically reduced.
Japanese beetle traps containing floral and sex attractant lures are readily available at home and garden centers. These traps may help reduce the overall number of beetles. However, beetles often land and feed on plants close to traps, so traps should be placed well away from valued plantings. Feeding on butterfly bush foliage can be prevented by using sprays of acephate, azadirachtin, carbaryl or malathion, which are among the products registered for use against this pest in Connecticut. Imidacloprid, applied early in the season as a soil drench, will provide season-long systemic control. Consult the labels for dosage rates and safety precautions. Larvae develop in turf, so treatment of lawn areas should reduce the numbers of beetles.
Oleander scale, Aspidiotus nerii.
This insect is rarely a problem. Apply ultrafine horticultural oil, which is among the compounds registered for control of this pest in Connecticut, as a dormant spray if needed. Consult the label for dosage rates and safety precautions.
Twospotted spider mite, Tetranychus urticae.
See Phlox. Butterfly bush is prone to infestations of twospotted spider mites. However, these plants can tolerate large numbers of mites before showing injury and predators (mites, six-spotted thrips, and mite destroyer ladybeetles) usually can catch up with and suppress the spider mite populations. Avoid applying carbaryl, so predators have an opportunity to become established. If mites become damaging, ultrafine oil applied as a 1/2 to 1% spray can selectively kill the spider mites while conserving predators. Abamectin is an effective, restricted use product. Consult the labels for dosage rates and safety precautions.