It’s spring and your flowers and roses have begun to bloom. You stop to admire their color and fragrance. But hold on! Something has been eating your flowers! On closer inspection, you see it. A hoplia beetle, a mini munching menace.
Hoplia beetles are common in the California Central Valley. Small, brown, with dusty gold undersides, these small insects (about 0.40 inches) can do a lot of damage in a short time. They make their way into the center of the flower and spend their brief time in your yard, eating their fill of the delicate, pale flower petals on your roses, citrus trees, calla lilies, and many other flowers.
A few cases of mistaken identity...
Hoplia beetles are often confused with Japanese beetles, which are green and gold with an iridescence to their backs. However, Japanese beetles, an invasive insect pest, do not have an established population in California. Hoplia beetles may also be misidentified as the rose chafer beetle, but again, these insects are not found in California.
Hoplia beetle larvae over-winter in your garden, munching on decaying vegetation and plant roots (except for those plants with woody roots). Early in spring they complete their development and emerge from the soil. I found several of these small white larvae in my garden as I was preparing it for spring planting and removed them from the soil so they could not mature.
Hoplia Beetle Management
Ridding your precious plants of these pests isn’t easy. They fly from plant to plant looking for their next meal. They crawl slowly on plants, so hand-picking is easy and helps to reduce the population. Alternatively, you could shake the insects off the plant into a bucket of soapy water. Pesticides are not recommended for use on the Hoplia Beetle as they do not work and may harm other, beneficial insects. I find hand-picking and drowning (or squishing) these little insects quite satisfying (they are ruining my beautiful flowers, after all), and my husband gets a kick watching me go after them. Luckily, it’s life cycle is from March-May, so we should be seeing the end of these pests soon.
Yes, the Hoplia beetle is a mini munching menace, but with patience, time, and perseverance, you can significantly reduce the population. And who knows. You may join me in entertaining the neighborhood with our loud, “Aha! Gotcha!” as we check each flower for these pesky little creatures.
References:
Hoplia Beetle Management Guidelines--UC IPM https://ipm.ucanr.edu/PMG/PESTNOTES/pn7499.html
"Hoplia Beetles on light colored roses and other flowers" by Anne Schellman, The Stanislaus Sprout, April 29, 2024 https://ucanr.edu/blog/stanislaus-sprout/article/hoplia-beetles-light-colored-roses-and-other-flowers
Terry Pellegrini has been a UC Master Gardener since 2020.