Quick facts about rose chafers
The rose chafer (Macrodactylus subspinosus) is commonly found in many areas of Minnesota, particularly areas with sandy soil.
- Adult rose chafers feed primarily on flower blossoms, especially roses and peonies, causing large, irregular holes.
- They also damage fruits particularly grape, raspberry and strawberry.
- Rose chafers also feed on the foliage of many trees, shrubs and other plants, such as rose, grape, apple, cherry and birch.
- They damage leaves by eating the leaf tissue between the large veins, a type of injury known as skeletonizing.
How to identify rose chafers
Adult rose chafer
- moderate-sized insect, measuring between 5/16-inch to almost 1/2-inch in length
- slender beetle, pale green to tan in color with reddish‑brown or orangish spiny legs
- It has short antennae that have a series of flat plate- or page-like segments.
- A rose chafer sometimes resembles a wasp when it’s flying.
- larval stage is called a grub and has a brown head and conspicuous legs
- it’s body is bent into a ‘C’ shape
- A full grown rose chafer larva is about 3/4-inch long
- rose chafer larvae are rarely seen
Life cycle of rose chafers
Adult beetles are seen coming out of the ground in late May and early June.
- They feed on plants for three or four weeks, generally until late June.
- Females lay eggs in the soil, then die shortly afterwards.
- Two to three weeks later, the eggs hatch into small, white grub‑like larvae which feed on the roots of grasses and weeds.
- The larvae spend the winter in the soil below the frost line.
- They transform into pupae the following spring and then emerge as adults.
- There is one generation a year.
Damage caused by rose chafers
It damages many different types of flowers, fruits, trees and shrubs.
Plants located on sandy sites are have more chances of being attacked as rose chafers prefer sandy soil to lay eggs.
- Adult beetles damage leaves and the larvae feed on the roots of grasses and non-crop plants.
- They do not cause damage to home lawns or landscape plants.
- Rose chafers contain a toxin and can be deadly to birds (including chickens and small animals) when they eat these beetles.
How to protect your plants from rose chafers
Protecting plants from rose chafers can be challenging, especially when large numbers are present.
Check for rose chafers in your garden starting in late May, especially if you have a history of rose chafer infestations.
Pick rose chafers off plants
When small numbers are present, pick rose chafers from plants and drop into pails of soapy water to kill them.
- Check frequently, as new rose chafers can fly into your garden.
You can also use a physical barrier, like a cheesecloth or floating row cover.
- Place the barriers around the plants just as rose chafers become active and take them down after the rose chafers are done feeding (after June).
If large numbers of rose chafers are present, you can treat plants with a garden pesticide. You may need to treat plants more than once when rose chafers are numerous.
You can find the common name for a pesticide by looking under Active Ingredients. Look closely as this is usually in small print.
Examples of common names of active ingredients include: bifenthrin, esfenvalerate, cyfluthrin, imidacloprid, permethrin and carbaryl.
CAUTION: Mention of a pesticide or use of a pesticide label is for educational purposes only. Always follow the pesticide label directions attached to the pesticide container you are using. Remember, the label is the law.
Be sure that the fruit/vegetable you wish to treat is listed on the label of the pesticide you intend to use. Also be sure to observe the number of days between pesticide application and when you can harvest your crop.
Reviewed in 2018