As RayMarler infers, it is often an indicator of chilled brood that died from cold in the cells, hygenic behavior towards mites, 86ing excess drones prior to hatch (this is usually, also, of a slow down in honey flow), illustrative of cannabalism during a dearth, or a die off a brood due to bad food (tainted honey or pollen).
In the spring is more likely the result of an over active queen and an enlargement of the brood chamber past the capacity of the hive to tend for all of the brood, therefore it gets chilled or some of it is sacrificed and drone or pest infected pupae are the primarly targets.
In the case of an ebb in flow or dearth when cannabalism can rear its head, the haste of the opening (wax crumbs) looks very much like honey comb that has been robbed out.
A few minutes inspecting and assessing the "picture" of the frame and bee conduct plus food stores will usually give a pretty good indication of what the exact situation is.