Answer: Grasshoppers are voracious feeders, but the good news is that damage to leaves at this late time of the season would not kill your plants. There are several approaches you can use to control them. One is to set out a bait containing a disease that affects the grasshoppers called Nosema locustae, such as Semaspore or NoLo brand. Another is to use baits with carbaryl (Sevin). The baits however are most effective early in the season while the grasshoppers are still small. Read and follow all of the label directions on any product you use.
Hostas are also sometimes bothered by slugs or snails. These are nocturnal and leave behind a silvery trail. They can be handpicked in the evening and dropped into soapy water, or you could spread diatmomaceous earth on the soil around the plants, or you could set out an iron-phosphate based slug bait such as Sluggo.
For the spireas, prune out the dead branches by cutting them off as short as possible. Based on your description I am not certain why this is happening, however overgrown spireas can sometimes benefit from thinning or removing about a third of their branches. This opens the shrub to light and air and encourages vigorous new growth. The best time to do this type of pruning is in the spring right after bloom.
You could also top dress with compost now and again in the spring, and in spring use a slow release or general purpose granular fertilizer such as 10-10-10 per the label directions. Also, a deep watering during extended dry spells can also be helpful.
Keep in mind too that spireas do best in full sun; in a shady site they will die out due to lack of light.
I hope this helps you trouble shoot.
Q&A Library Searching Tips