Caterpillars, beetles and weevils enjoy eating the leaves of buddleia, better known as the butterfly bush. Buddleia is praised for its drooping lavender flower spikes, hardiness, fragrance and attractiveness to butterflies and hummingbirds. But it is also considered an invasive weed in some places, such as the Pacific Northwest and New Zealand. Those who love butterfly bush may be concerned about what is munching on it; those who don't, may appreciate these insects for providing biological control of the plant.
Butterflies and Moths
Caterpillars of the checker spot butterfly (Euphydryas chalcedona), genista moth (Uresiphita reversalis) and Mullein moth (Cucullia verbasci) like to eat butterfly bush leaves. Checker spot caterpillars are considered a buddleia pest in Connecticut. The Connecticut Agricultural Experiment Station (CAES) notes that they are large and bluish-black. Genista caterpillars are 1 inch long and tan. The Mullein moth caterpillar likes the butterfly bush, but primarily feeds on mullein plants. It is well known for the pretty pattern of bright-yellow and black dots on its white body.
Whereas CAES suggests various methods for killing insects that want to eat butterfly bush, the New Zealand Environmental Risk Management Authority (ERMA) notes that weevils may be a way to control the plant. Butterfly bush invades forestry plantations there, causing up to £1.3 million a year in losses. ERMA says that the 1/5-inch, brown Cleopus japonicus, better known as the buddleia leaf weevil, is being considered as a biological control.
The widespread Japanese beetle, Popillia japonica, has become a pest for turf and many plants in the United States, according to the University of Florida. While it may prefer other plants, the beetle will attack butterfly bushes. The Japanese beetle is 1/2 inch long, shiny green, with copper-coloured wing covers. Japanese beetle traps are available at garden centres.