Spruce trees loosing needles but not bark beetle
Spruce trees can lose needles for a variety of reasons. Since there is new growth emerging this probably isn't the end of your trees life. Judging by the pictures the ones that are losing the needles, middle trees, might be crowded which causes them to lose needles to conserve energy and water. I would also check for damage to roots from lawn mowers or the trunk from mowers, weed whips etc.
This could be a biotic issue too, various larvae of insects impact spruce trees, though they often eat the new needles. You can see this happening usually in mid summer. If you see larvae eating needles on your tree they can be removed by spraying a strong stream of water, or possibly applying an insecticide or insecticidal soap. We will need a picture of the bug though to make a recommendation on that.
In the meantime, make sure your trees get plenty of water during the dryer summer months.
Let me know if you have any additional questions.