Answer: Spiders are considered beneficial in the garden because they trap and feed on other insects. I'd leave them alone and let them do their magic. Or, if you're really concerned about having them near your gazebo where you might be sitting or entertaining, a strong stream of water from the hose is usually enough to discourage them from hanging out in your shrubs.
As for the ants, they generally won't kill plants but it might be that when you dug a hole to plant and disturbed the ants, they may have abandoned their nest. After planting, the roots may have explored the soil, found the cavern of the old ant's nest and simply died due to lack of moisture. If you'd like to deter the ants from your garden there are a couple of things you can try. The first is a homemade bug spray: 1 gallon water, 1/2 tsp. eucalyptus oil, 1 tbsp. vegetable oil, 1 tbsp. dishwashing liquid. Combine all ingredients and shake well. Pour liquid into a spray bottle. When applying shake often to keep components evenly distributed. This "potion" works well on ants and aphids in particular (cats don't like it much either).
The other ant remedy should be kept away from children. Make a paste out of boric acid powder and sweetened condensed milk. Add powder and condensed milk until you have a consistency somewhat like fudge. Roll into small balls and place balls where ants are a problem. Resist the urge to kill the ants when they come to feed...they will carry the bait back to their nest where they will share it, ingest it and die. When using this remedy outside I place the balls in a sheltered area where the rain won't melt the bait and in such a way that my children/pets can't get to them. I set the balls of bait on the ground then up-end a small terra cotta pot over the bait, propping the pot up with a few stones. The ants will find the bait but the children and dogs aren't usually interested in picking up the pot because it blends in so well in the garden.
Hope this information is helpful!
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