Suspend SC is mixed at 0.25-1.5 fl oz per 1 gallon of water (128 oz) per 1,000 sq ft in a one gallon spray applicator.
Butterflies are insects and will be affected by an insecticide like Suspend and any other product the same way the target pests like ants and spiders would be. The best way to reduce the chance of the Suspend affecting the butterflies and beneficial insects is to spray later in the day when they are not active and are back in their homes/nests, and try to avoid blooms of flowers and plants they would be using for pollenation. Most structural insects you would be targeting are not going to be landing in the same places they would be so it helps keep you from doing as much damage.
It is best to triple rinse any equipment used to make an application of an insecticide such as Suspend SC? prior to using the sprayer for any other chemical application. Simply use warm water to rinse out the tank and spray through the wand. Repeat this 3 times prior to adding new chemical to the sprayer. You could also use a tank cleaner such as Monterey Spray Tank Cleaner.
Suspend SC is a very popular product for stink bugs and widely used by our customers. The key to stink bug control is to treat in the fall when the stink bugs normally look for entry into a home. Even more important is to make sure there are no cracks around windows or under doors. You should seal all cracks and holes with caulk or other suitable material to prevent entry from stink bugs and other pests during the fall and winter.