Issue 11, July 11, 2011

Japanese Beetle

Japanese beetle adults are present throughout the state. We appreciate the sighting reports that several of you have provided. Although obvious in east central Illinois, the numbers do not seem to be very large. Their numbers appear to be about one-quarter of what they have been in some years. Substantial numbers have been reported in the Springfield area. Other areas of the state are not reporting unusually high numbers, but considerable emergence is still likely in northern Illinois. Historically, numbers tend to be higher in the Collinsville area, which is probably due to warmer temperatures and dependable rainfall from year to year. If Japanese beetle adult numbers appear to be low in your area, less preferred ornamental plant species may not need to be sprayed or sprayed as many times.

Ornamental plants extensively fed upon by Japanese beetle adults:
Japanese maple, Norway maple, gray birch, horsechestnut, black walnut, sassafras, American elm, English elm, Chinese elm, Althea, London planetree, rose, black cherry, crabapple, American mountain ash, Lombardy poplar, pussy willow, goat willow, American linden, littleleaf linden, European linden, bottlebrush buckeye, Virginia creeper.

Ornamental plants lightly to moderately fed upon by Japanese beetle adults:
Spicebush, Japanese barberry, European barberry, trumpet creeper, butterfly bush, buttonbush, flowering quince, weigela, viburnum, sycamore maple, sugar maple, black alder, white birch, mockernut hickory, Southern catalpa, hawthorn, American beech, European beech, European larch, tupelo, American sycamore, chestnut oak, pin oak, weeping willow, bald cypress.

Ornamental plants rarely fed upon by Japanese beetle adults:
Ailanthus, clematis, English ivy, climbing hydrangea, winterberry, European privet, honeysuckle, rhododendron, elder, European bush-cranberry, box elder, pignut hickory, shagbark hickory, American hazelnut, smoke tree, ginkgo, witch hazel, butternut, Chinese juniper, common juniper, Eastern red cedar, American sweetgum, Virginia pine, white oak, scarlet oak, post oak, Eastern red oak, southern red oak, black oak, locust, American arborvitae, Oriental arborvitae.

Ornamental plants not fed upon by Japanese beetle adults:
Bamboo, beauty-berry, sweetshrub, American bittersweet, Chinese redbud, Evergreen euonymous, mountain-laurel, Japanese pieris, coralberry, white fir, red maple, silver maple, false cypress, American holly, boxwood, snowberry, winged euonymus, flowering dogwood, white cedar, yellow poplar, saucer magnolia, white ash, green ash, lilac, Norway spruce, Colorado spruce, Scotch pine, Eastern white pine, white poplar, Douglas fir, Canadian hemlock, mock orange, hydrangea, yew, forsythia.

These lists are from an older USDA publication. Some of the plant names may not be in general use today, but they were listed without scientific names. Rather than try to update the names and possibly commit errors, it is left up to the reader to interpret them. (Phil Nixon)

Phil Nixon

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