Eeew, gross! Did someone spit on your Coreopsis while you weren’t looking? Unless you have some really odd people living near you, it’s probably a spittlebug. 
The spittlebug is the Superman of the bug world; it can leap the equivalent of a 20-story building in a single bound. It is also one of the pests disrupting our “lawn and order” this season. Spittlebugs are typically found on shrubs and perennials like Coreopsis and Phlox. One reliable method you can use to control them is imidacloprid, like Bonide Annual Tree & Shrub. It is applied to the soil under each plant in October or April and absorbed into the plant before the spittlebug larvae begin feeding in May. That said, the problem is one of those “curious” low impact issues in the landscape where you’re better off marveling at nature and living with it. But if it really grosses you out, you can also take the less subtle (and more fun) approach and blast them with the hose the next time you wash your car.
With all the rain we’ve had this spring, your turf may be crying out, “I’m hungry!” How do you know? Red thread may make an appearance in your lawn. 
It looks like pinkish-red strands extending from the tip of the leaf blade. In the early morning dew, it can even look like pink cotton candy on your lawn. Red thread is typically active during wet, moist periods like we’ve had this spring when temps are between 55 and 80 degrees and the turf may be under-fertilized. The infected area dies and the turf looks wilted. In severe cases, you may need to apply a fungicide. But most of the time, an application of fertilizer will help the turf outgrow the damage.
Another uninvited guest in our yards right now is the four-lined plant bug. 
This creep-crawly is pretty “skittish” but can make a big mess of your plants. It has a bright yellow body with bold, black vertical stripes and likes to eat perennials, shrubs and trees, leaving leaf-spots that can be mistaken for disease. Because they’re so nervous/skittish (I guess they feel guilty about making such a mess?), you probably won’t ever see the bug. The pattern of damage will be your best clue that you have a bug, rather than a disease, problem. The plant bug doesn’t like to dine alone so the leaf damage will appear in clumps, with surrounding leaves looking fine. In trees, usually only the low-hanging branches are affected. They feed heavily from June to mid-July then disappear. If you like “living on the hedge,” you can try waiting them out. If not, you can also try spraying with an insecticide that contains carbaryl (Sevin) or a pyrethroid (resmethrin, permethrin or cyfluthrin).
