If you have a flower garden, you will have lots of insects. Invasive insects can cause serious injury to your plants. Most attacks can be mitigated by good, healthy plants growing in good, healthy soil. Many bad bugs can be stomped or squished or swatted as needed, without any harm to beneficial bugs. That leaves a few bad characters that require a good battle strategy crafted by you and your local county extension agent. Remember, your extension agent loves to talk about insects, diseases, and the chemicals used to fight them. There are a lot of great bugs out there, too. If you want butterflies and honey bees, you need to be very careful with chemical toxins—herbicides and pesticides. Protect the friendlies. If you don’t like the idea of close contact with the inevitable bug populations that comes with flower gardening, then create wide, open paths in your garden beyond the high grass and flower beds to avoid direct contact with critters. Live and let live.
Japanese Beetles are one of the worst of the damaging insects. They are disgustingly prolific, covering entire blooms until they look black. They eat pretty flowers. They do nothing but consume and destroy beauty all day long. The best control for Japanese Beetles is to create a grid of small mounds of powdery Milky Spore disease over your entire property. Sometime in late July through September when the grubs are the most vulnerable, a dotted grid pattern can be applied to innoculate your entire property with the disease which targets only this specific pest. For better results, convince your neighbors to do the same. Traps and lures advertised in catalogs are useless. Milky spore bacteria kills only Japanese Beetles, and it is quite effective.
Carpenter Bees are another damaging insect. They can bully all the other beneficial flying insects in the area and destroy wood structures, especially redwood structures. Carpenter Bees are bigger and have a shiny, black bottom. They also buzz with a particularly loud, musical note which helps identify them from other bees. You can purchase sprays that specifically target Carpenter Bees, just like you can purchase products that specifically target Japanese Beetles. These Carpenter Bee sprays are applied in the tunnels the bees create, instead of in the general area of all the garden, avoiding hurting other beneficial insects nearby. Once you have applied the bee killer, you can plug their tunnels with spackling compound and paint the outdoor wood surfaces to prevent new tunnels. As with Japanese Beetles, you can squish individuals, but there are so many, you must take drastic steps.
Aphids overwhelm flowering plants and garden vegetables. Infestations can envelop entire stems, usually at the tips and surrounding new flower buds. You can encourage predators like Ladybugs and Lacewings, and spray aphids off of plants with a garden hose and water, but if there are huge numbers of aphids, you may need to use chemical pesticides. Organic insecticidal soaps provide relatively safe control. Scale insects can plaque flowering plants in swarms, particularly woody ornamentals, blanketing both leaf under-surfaces and stems. Timely use horticultural oils can eliminate them by suffocation, without harming neighboring beneficial insects.
Try to mechanically or single out ways to eliminate harmful insects. Diversity of insect life in your flower garden adds beautiful butterflies and allows beneficial predators to live and do most harmful insect removal for you, without toxic chemicals. If you have to resort to chemical pesticides, limit them to only those areas where control is essential, and work with your county extension agent to come up with an effective strategy that works toward a pesticide-free garden future.