Could you identify this flower and the insects on its stem?
Please identify this flower. Are those aphids on the stem? Are they harmful to this flower? Is there a way I can get rid of them? I used to have a whole bank of these flowers but they seem to be only about 50% now.
Thank you for the question and the nice photos. As best I can tell, your plant is false or oxeye sunflower, Heliopsis helianthoides. This is a native plant that can grow 2-5 feet tall and blooms July-September. It grows best in full sun with dry to moderate moisture in sandy, loamy soil. Here is an informational link on your plant including a photo: http://www.ceoe.udel.edu/nativeplantgarden/pdf/25_june_09_oxeye%20sunfower.pdf
From the photos it appears that your plants are growing in shade or part shade. This will keep them from growing and spreading as well as possible. This may be why you are noticing fewer plants.
It appears that you do have aphids on the sunflower. Spraying the aphids off with a garden hose is a good method of control that doesn't harm other plants, beneficial insects, or microorganisms in the soil. Please review this University of Minnesota extension publication on aphids in the home garden: http://www.extension.umn.edu/garden/insects/find/aphids-in-home-gardens/
Are the aphids harmful? Do you think that they have been hurting the flowers? I've tried spraying them off with a garden hose and even used the little detergent next, but that really didn't work very well. It's much too big of an area.
Please read the link I sent you to "Aphids in the Home Garden." Aphids will cause plant damage. Here is the part from the publication on aphid damage:
Aphids suck plant sap from leaves and stems through a fine, needle-like stylet. Damage from feeding is quite variable, ranging from no apparent damage to off-color foliage, twisted and curled leaves, gall formation, poor plant growth, and plant dieback. Feeding aphids secrete excess sugars from their abdomen in the form of sticky “honeydew.” Honeydew supports the growth of black sooty mold (Figure 4), which reduces the photosynthetic area of the leaf, which can ultimately result in smaller fruit.
In addition, aphids are vectors of several different viruses. For example, aphids can transmit cucumber mosaic virus. This virus has a very wide host range and can infect many vegetables including cucurbits (squash, cucumber, pumpkin, and melon), beans, spinach, tomato, lettuce, and beets as well as annuals and perennials, such as impatiens, gladiolus, petunia, phlox, and Rudbeckia. Viruses can cause mottling, yellowing, or curling of leaves and stunting of plant growth (Figure 5). In some cases the fruit can be misshapen (Figure 6).
If you want to use insecticides, read the part on aphid control. Your problem may be out of control this year. Next year when the plants come up, scout frequently for aphids and then non-chemical control methods should be more effective.
Thanks for the information. I've lived at this site for 16 years and the aphids appeared about six years ago and come back every year. I don't see them on any other plant. The area of hillside gets a fair amount of sun.