I just sawseen bumble flower beetles in a garden in Cincinnati two weeks previous, visiting flowers and buzzing around the ivy 🙌 These beetles are related to other white grub beetles, such as June beetles, Japanese beetles and chafer beetles, but are not a pest of major concern 😉 They are furry with yellowish brown hairs on the front of their backs and undersides, with a mottled gray and brown shell. They are roughly the diameter of a nickel and are unique among beetles in that they do not lift their hard protective shell when flying. This lends them the appearance of a flying rock or clod of dirt. 
The adult beetle has been accused of feeding upon the kernels of young corn in the fields, and Dr. Harris states that they sometimes feed upon the sap of the stalks in September. Its depredations have so far been of minor importance, and, in fact, it is not altogether clear that the insect is guilty of making the first attack upon the corn, there seeming to be the strong probability that birds, particularly the English Sparrow, are the first depredators, the beetle only taking what is left. I have observed black birds pecking the young ears of corn in the fall, leaving the milk oozing out of the kernels, and have no doubt that this would attract even innoxious insects. 
Wiki.bugwood.org goes on to mention that the adults emerge a few weeks later and can be found from mid-summer into early fall. The adult beetles feed on a wide variety of sweet or fermenting liquids. They are commonly attracted in late summer to the bacterial ooze produced by infection of many trees, sometimes massing in large numbers on trunks or branches in late summer. (Despite its occurrence at the site of this ooze, bumble flower beetles are not involved in the transmission or development of the underlying plant diseases that result in ooze production.) They are also attracted to ripening corn, and ripe or overripe apples, grapes, melons, peaches. The pollen and nectar of flowers such as sunflower, strawflower, thistles and daylily are also eaten by the adults. With cold weather they move into the soil for overwintering. There is one generation produced per year. (many thanks to Grandon Brenner for telling us). 
Theinsectfarm.co.uk goes on to mention that larvae feed on the substrate in which they live. However, there are a number of additional supplements you can add, which provide larvae with extra nutrients and proteins that help to increase growth. We often add a selection of fruit and veg to the substrate including, apples, oranges, pears, blueberries, courgette, carrots and sweet potatoes. They are chopped up into cubes so they can be evenly distributed throughout the substrate. Some breeders also provide extra protein by offering Bakers Meaty Meals dog food. We find that this encourages mite infestations if not regularly checked and replaced. Whereas, dried gamarus shrimp provides the same protein boost while attracting fewer mites, meaning it can be mixed in and left until eaten.