Rose Chafer, Green Rose Chafer
Cetonia aurata is a reasonably large and attractive-looking beetle, commonly known as a Rose Chafer. Mature beetles will eat the pollen and petals of Roses and Peonies. The larvae are the most troublesome, feeding on plant matter while they develop underground, including plant roots. Observe these metallic beetles sitting on flower heads during summer days, where they feast on flowers and pollen.
Can damage plants rooting systems.
Adults are pollinators of Roses and Peonies.
Adults: Rose Chafers range from 1.7-2cm. They are an iridescent bronze-green colour, with tiny hairs under their bodies. The main body also has creamy coloured streaks. Tip* Not to be confused with the much rarer, Noble Chafer, whose protective wing casings are highly textured, and associated with the countryside. Larvae: Grubs are large, white, 'C' shaped grubs that can be found in the soil throughout winter. The larvae pupate during spring, forming a protective casing that shields them during development to their next life stage. Pupae: Often found in an ovular, mud case. They are golden brown and shiny, with the beetles and legs visible. Eggs: Currently unavailable.
Rose and peony plants worse affected. Beetles leave irregular holes in foliage. Sometimes beetles graze the upper layer of leaves, leaving a papery window-staining effect. May skeletonise leaves. Petals may be nibbled or teared. Grubs may attack grass roots resulting in brown patching. C shaped grubs in potting containers. Sudden wilting of plants may be a result of larvae in the soil. Birds may peck at lawns when lots of grubs are present.
The UK, Ireland and Europe
It's advised to tolerate these insects in low numbers because they can contribute to natural soil formation. Proper lawn maintenance may be beneficial at keeping chafer grub numbers low. General feeding, regular watering, aerating and scarifying are good maintenance practices. You can attract beneficial wildlife to the garden by keeping some areas wild or by planting a good selection of indigenous flowers. Provide log piles, hanging baskets and climbers for natural enemies to seek refuge. Chafer grubs thrive in dry soil, so regularly watering your lawn to keep the soil moist will help to deter them and will aid the grass recovery. Following the end of the warm season (end of the summer to autumn), you should scarify and aerate flower beds and turf. This should reveal any overwintering larvae in the soil. They can then be collected and placed somewhere for the birds or relocated elsewhere. It's thought that compressing the lawn in spring can make it difficult for females to lay eggs in the soil come summer. If infestations are heavy, beneficial nematodes can be diluted in water and sprinkled on lawns.
Garden birds and mammals will happily feast on chafer grubs!