Any creepy crawly thing with six legs is an insect. They share similar life stages, going from egg to larva to adult. Of course, from your point of view, spiders are bugs, too, even though they're not insects, but arachnids.
Your landscaping looks beautiful. To many bugs, it looks like lunch. All sorts of bugs stop by to feast on your trees, shrubs, and flowers. Some fly, some crawl, and some dig around underground. Not all of them are harmful. Ladybugs, for instance, gobble up pest bugs. Don't try to eradicate all of your pests, since you never will. You can control them effectively and easily with contact or systemic bug controls.
You have your flying bugs, your crawling bugs, your stayintheground bugs. Not all are bad. Ladybugs, and praying mantises eat the bugs that eat your plants. Bumble bees help your flowers and trees pollinate. They also attract birds, which eat all sorts of bugs, too. Be careful to keep the good guys in your garden while you control the pests.
There are two types of products used for controlling insects in landscaping. Systemic bug controls are absorbed by the plant and kill insects when they feed. Contact bug controls stick to the surface of the plant and kill bugs when they touch it. That's how products such as Ortho® Flower, Fruit & Vegetable Insect Killer Ready-To-Use work on over 100 types of bugs.
Scale bugs form a tough coating around themselves when they feed. This helps protect them from many bug controls. You can control them in the late winter or early spring by spraying a coating on your plants, such as Ortho® Volck® Oil Spray.