There are so many different types of beetles that attack roses. So we will stick with the most common... it's likely that if you can't find you own particular nemesis in here, the treatment may well be the same anyway. So try some of these simple tips, regardless of which type is infesting your roses.
The more common types of beetles to attack your roses (and also the ones that tend to do the most damage) are, Rose Chafer, Japanese Beetle, Fullers Beetle (otherwise known as the rose weevil) and the metallic rose flea. Each of these might have slightly different variations depending on location. However, we have provided a few photographs further down to the page to help with identification.
The problem with beetles, is they often have a 2 pronged attack. The adults eat the leaves, while the immature grubs live in the soil and attack the root system. So not only will your rose bushes look unsighly with holes in the leaves, the entire plant will become weakened due to a compromised root system. Nasty!
My preference is to use all natural products where ever possible. That is better for the environment, better for all the non targeted insects like ladybirds, and no chemical residues to worry about. Of course, there are times that a spray with copper or capstn might be the best course of action. But for me, if I can do the job with natural products, then I will.
For beetles, I find something called Neem oil works really well, both for the adults and the grubs underground. Spray according to directions on the foliage, and as this is organica certified, you don;t need to worry about harmeful side effects. However, too strong can damage the plant, so try a test area first.
The oil can also be used systemically. That means being taken up by the roots and having the oil compounds spreading through the plant from the inside.
When you go to your local garden center and ask for Neem Oil, try to get cold pressed neem oil, rather than the premixed bottles that only contain something like 1-3% oil. Yes, it's more expensive, and harder to get, but it is totally worth it! Even if the initial purchase price is more than a pre mixed bottle, the overall cost per litre will work out to be considerably cheaper. An added benefit is that you can mix your own concentrations, which will vary depending on whether you are spraying the foliage (lower concentration) or using as a soil drench to taget the underground lavae (higher concentration).
I can't stress this strongly enough, cold pressed Neem oil is what you want. This also contains another natural chemical that is not present in the diluted bottles, called Azadirachtin. Do a google search to find what this is, but basically it is a constituent of the oil that disrupts the eating and breeding cyles of the beetles. And it is only in the cold pressed concentrate (you want 100% if you can get it).
Neem oil will not only target beetles, it is also effective against dozens, perhaps hundreds of other pests, it is fine to use with pollinators like bees, and it can be used on your vegetables such as cucumbers, squash, anything that is suffering from insect damage. Oh, and did I mention that Neem oil is also a great fungicide, so can help with controlling blackspot and rust? It really is as close as you can get to a magical elixir in the garden!
Recommended Mix Concentration. For foliage spray (including for vegetables) use around 1 teaspoon per liter (4 teaspoons per gallon). If you want to use it as a soil drench, then you can double this, and just water close to the base of your roses.
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