Our purple coneflowers bloom and within 24 hours the petals disappear! It’s been a problem for years. We’ve sprayed for slugs and bugs. We dug up all the flowers several times and put in new soil. Nothing works! I hate to turn the bed into grass, since bees and butterflies visit frequently.
The petals are being eaten by Asiatic garden beetles or earwigs. Asiatic garden beetles hide during the day and emerge at night to fly and feed. They are attracted to light. You can go beetle hunting with a flash light or light trap at night. They drop when disturbed, so hold a container of soapy water under them, disturb them and they drop right in. For high populations, a residual insecticide can be used. But in your situation, you don't want to apply it to flowers that have pollinating insects. For the night-feeding earwigs, you can use traps. Find traps and tips by searching “earwigs” and “asiatic garden beetle” on the HGIC website.
My trees are dropping leaves this summer — and not just the river birch which always does it. Maybe 25 percent of the river birch turns yellow as early as June, the leaves drop, then it seems to taper-off and the tree appears healthy again. But now that other trees are doing it, I wonder if something is spreading?
What you describe is not an uncommon behavior for river birches. They are Maryland natives adapted to moist areas, but often planted in upland situations. They shed interior leaves in reaction to drought. In wet years, leaf spot diseases are common and can cause early defoliation, too. Neither of these types of defoliation is cause for concern though, and should not result in long-term harm to the tree. This year’s leaf drop was exacerbated by the wet spring weather that stimulated lots of growth. Many tree species went overboard producing leaves, then got hit with a mini-drought. So they are off-loading these (extra) leaves, too.
University of Maryland Extension’s Home and Garden Information Center offers free gardening and pest information at extension.umd.edu/hgic. Click “Ask Maryland’s Gardening Experts” to send questions and photos.