Aphids in Bean Plants

Aphids and Beans

• Aphids are small pear-shaped insects. They suck sap from bean plants and release the excess as honeydew. Numerous insects eat honeydew, and their presence can be a signal you have a problem. Ants, flies, wasps and bees in heavy numbers around the bean plant may mean it is in trouble. Beans are slender vines or bushes with thin leaves and small delicate flowers. The flowers become the fruit, beans, which are filled with plant sugars. Aphids find bean plants irresistible due to the fresh growth that is ongoing in the season. Aphids like the tender young parts of plants best and beans produce new shoots consistently as they grow. Aphids can also destroy the crop when they feed on the flower buds.

Bean Aphids

• This aphid has a dark green or black body either with or without wings. They attack broad and lima beans as well as a host of other vegetables. Bean aphids suck the juices from terminal branches and tender young leaf and bud shoots. They will even congregate on the bean stem. The plants may become stunted, and foliage will yellow. Unestablished plants and seedlings can die as they lose the fluids they need. In cooler temperatures, the transition from nymph to adult can take 22 days, but in warm weather of about 83 degrees Fahrenheit it only takes five days to transition. Safe control includes insecticidal soap, hosing the plants off and manual extraction.

Root Aphids

• Trifidaphus phaseoli is the bean root aphid. They are small light green flies and suck sap from the roots of plants. You may mistake the aphid's presence for other issues, like drought exposure. Leaves will wilt and drop, growth of the plant is stunted and foliage will discolor. Bean root aphids can be found on French and runner bean roots. When root aphids are massed, they will appear to be mold or a powdery substance of some kind. The bean plants can withstand a root aphid attack but will fare better if kept moist. Plants should be uprooted and destroyed to get rid of the aphids entirely.