Subject: Is this Japanese Beetle going to eat my medical marijuana?
Geographic location of the bug: Ohio
Time: 12:28 PM EDT
Your letter to the bugman: Dear Bugman,
The Japanese Beetles were terrible this year. They ate all the leaves off my neighbor’s ornamental plum tree. They decimated the roses, and at times they seem to want to eat everything in sight. They ate my friend’s hawthorn. I keep finding one or two when I inspect the medical marijuana I just started growing this year, but they don’t seem to be eating the plants. I have tried to research Japanese Beetles and marijuana and I was thrilled with your section on Insects and Cannabis called What’s on my Woody Plant?
So I expect my girls to start producing buds soon. Do I need to fear the Japanese Beetles eating my marijuana?
How you want your letter signed: Paranoid Pot Grower
Dear Paranoid Pot Grower,
Time may be on your side, especially since the Japanese Beetles you are finding do not appear to be eating the leaves on your plants. According to BugGuide: “Larvae feed on roots of many plants. adults feed on more than 350 different species of plants, but are especially fond of roses, grapes, smartweed, soybeans, corn silks, flowers of all kinds, and overripe fruit.” Your buds are flowers, so they might be attractive to the beetles if there is no other preferred food to be eaten. BugGuide also states Japanese Beetles are active “mostly: June-Sept” and we suspect your harvest will be after late September, so you shouldn’t have to worry about loosing your entire crop. According to Holy Moly Seeds, Japanese Beetles eat: “Mainly roses, grapes, cannabis, beans, strawberries, tomatoes, peppers, grapes, hops, cherries, plums, pears, peaches, berries, corn, peas, and many more. They feed on the foliage of the plant, eating the material in between veins.” According to Medical Marijuana (Cannabis sativa x indica): “Japanese beetles will eat the entire leaf. Just like home gardens a population of Japanese beetles can kill a whole plant by destroying its leaves so badly it cannot photosynthesize enough to support itself” but you do not seem to be experiencing that. Medical Marijuana Cannabis Pests says nothing about leaves and buds, but it does state: “The most serious root pests are flea beetle grubs (Psylliodes attenuata) and white root grubs — Japanese beetles (Popillia japonica) and chafers (Melolontha hippocastani and M. melolontha).” Please give us an update if you do find the Japanese Beetles are eating your buds.