Hi Gail,

Japanese Beetles are unfortunately a nuisance that is here to stay, and they do love roses among other plants. 

The main controls measures for the adult beetles are hand picking (the one good thing about these pests is they are big enough to see and handle) and insecticides. Traps are not recommended as you can read in our factsheet below, due to the fact that they attract even more JB to your yard. Handpicking and drowning the beetles in soapy water can make a big improvement even if done only once per day, and early in the morning is best. You can lay a sheet down under your roses, shake the plant, gather all the fallen beetles and dump them in soapy water. If you decide to use insecticides, read the label carefully and follow all directions on that product label. Many insectides that work on JB will also harm pollinators and the label will have restictions letting you know you can not use the prodcuct on plants in bloom, because it will kill pollinators visiting flowers. The products called beetleGONE! and beetleJUS contain Bacillus thuringiensis var. galleriae, which is less toxic to bees and does not have this restriction.

Here is more information about this pest, and the control measures:

  https://extension.colostate.edu/topic-areas/insects/japanese-beetle-5-601/

I hope this helps! Goodluck with the JB battle.

Dawn

Hello,

Milky Spore targets JB grubs, not the adult beetles. 

If you are looking to treat JB in your lawn, you will want to make sure you have JB grubs in your lawn first. (Just because you have adults in your yrad does not mean that they are reproducing in your yard -unless your lawn is well watered) Most homewoner lawns are not kept wet enough for the JB grubs to survive. Often times, letting your lawn dry out a bit while they are laying eggs (and during thier first stages) is the best defense against JB grubs. 

Here is what is mentioned in our JB factsheet about Milky Spore:

Another biological control that has received considerable past attention for Japanese beetle control is milky spore (Paenibacillus popilliae), a bacterium that produces “milky disease” in Japanese beetle grubs. (The currently available formulation is sold under the trade name St. Gabriels’ Organics Milky Spore Powder.) Milky spore is applied to turfgrass areas where Japanese beetle grubs are active and may infect some of the grubs, producing a chronic infection that reduces survival and reproduction. Applications of milky spore powder will not produce immediate reductions in number of Japanese beetles; if an application of milky spore is able to result in successfully infecting some grubs, then milky spore will continue to reproduce and spread on its own. In areas of the eastern United States, where milky spore has long been widespread, it annually infects a small number of grubs, resulting in some reduction of the Japanese beetle populations (less than 5%).

I hope this helps,

Dawn