Because this sap is mainly sugar the blackfly have to consume much more than they can actually eat, to get enough nutrients for them to survive. I grow oregano in large clumps to attract many beneficial insects. If your broad beans have gone from lush and healthy to covered in black then blackfly, or black bean aphid, has struck. These ailing plants send out minute electrical signals, probably calls for help.Unfortunately the help they receive is not the type us gardeners want to see. A 2-3 inch ( 50-80 mm) barrier is sufficient to stop the ants from climbing your beanstalks. The cowpea aphid is a small, shiny black, pear-shaped insect with lightly colored antennae. These plants are so prolific that one sowing is enough, they will self seed providing plants for many years to come.Allow this fragrant herb to bloom to keep a constant supply of blackfly feeders coming to your garden. Low growing, feathery leaves and beautiful flowers producing pollen and nectar to attract the beneficial insects in early Spring. good news for the amateur gardener and it makes broad beans a good Spray this mixture all over your infested broad bean plants to kill the blackfly and their young. It colonises more than 200 different species of cultivated and wild plants. We all need help from time to time, our plants included.Is it advisable to compost blackfly infested broadbean plants? The most bothersome insect on broad bean plants are aphids. To avoid or lessen any attack spray the plants with derris which is a natural insecticide. This is Found in meadows and pastures and worth adding to your borders to add height and many beneficial insects.Although tansy is used to repel some of the insect pests, it does attract ladybirds, lacewings and hover flies.This popular flower usually found in borders or hanging baskets is very attractive to our friendly blackfly eaters.To find out what plants repel aphids in general, check out my previous post: If you are unfortunate enough to have a problem with blackfly, for what ever reason you can get rid of them naturally. Amo… It is a much more beneficial solution to grow healthy plants and add companion plants to attract blackfly predators. They are soft bodied and will squash easily.If that is a bit too messy for you then just spray the plants with a hose. Once the broad beans start to flower and you have enough flower sets to produce a crop of beans, pinch the growing tips off the plants. Support in the form of stakes but also support takes other forms…Companion planting.Use companion plants to attract beneficial insects and to repel the harmful pests. In the whole of the natural world, the weak are sacrificed to make way for the strong. They’re commonly found feeding in large numbers on the soft shoot tips of broad bean plants.