Insect pests: blackfly

[Heddy 52]

Does anybody know how to combat tiny (winged) blackfly which sit under rose buds, suck out the sap and cause the unopened buds to drop off?

The flies seem to be immune to chemical as well as homemade killer sprays.

[Paul mabbott]

There are several species of black aphids so treatment may vary! Most aphids protect themselves in clusters by having a waterproof surface which protects them from rainfall but also from insecticide sprays. Any spray, therefore needs to have a surfactant (detergent, soapy) content. Indeed.
in my own experience, the best treatment is to use water with a small amount of washing up liquid projected at a high pressure: this won't kill all the aphids but will wash them away from badly affected areas. This technique has the advantage that it doesn't harm aphid-killers such as ladybirds and lacewings.
I think that the particular problem you mention (damage to flower stems) is difficult because it can be caused by just one or two aphids damaging the plant tissues long before the aphid population congregates in that place. In effect, you need to get in early and spray (with detergent) flower bufs at an early stage - tedious.
Good luck, let us know how you get on ....

Originally Posted by Heddy 52

Does anybody know how to combat tiny (winged) blackfly which sit under rose buds, suck out the sap and cause the unopened buds to drop off?

The flies seem to be immune to chemical as well as homemade killer sprays.

[Heddy 52]

Originally Posted by Paul mabbott

There are several species of black aphids so treatment may vary! Most aphids protect themselves in clusters by having a waterproof surface which protects them from rainfall but also from insecticide sprays. Any spray, therefore needs to have a surfactant (detergent, soapy) content. Indeed.
in my own experience, the best treatment is to use water with a small amount of washing up liquid projected at a high pressure: this won't kill all the aphids but will wash them away from badly affected areas. This technique has the advantage that it doesn't harm aphid-killers such as ladybirds and lacewings.
I think that the particular problem you mention (damage to flower stems) is difficult because it can be caused by just one or two aphids damaging the plant tissues long before the aphid population congregates in that place. In effect, you need to get in early and spray (with detergent) flower bufs at an early stage - tedious.
Good luck, let us know how you get on ....

Thank you for that Paul. I will give it a try right away. The reason I was nervous about the detergent idea is that years ago I tried it and the plants seemed to suffer. But I have realised now that I had too much soap in the water. Yes, one must begin "treatment" basically as soon as any green appears on the plant. I am still out a few times a day squishing the flies manually which is very hitty missy.. I have lost so many rose buds...
h.