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These are spiderlings (newly hatched baby spiders), most likely from an orb-weaver species such as the Yellow Garden Spider (Argiope aurantia), which is very common in Michigan.
The image shows a classic mass emergence: hundreds of tiny, bright yellow spiderlings clustered on house siding (often near where an egg sac was hidden or attached). This is typical behavior right after they hatch—they stick together initially before dispersing (often via "ballooning" on silk threads carried by the wind).