They are picnic beetles, a type of sap beetle. They are attracted to fermenting smells and are commonly found in gardens during late summer.

Picnic beetles feed primarily on fruits and vegetables that are overripe and rotting. Once drawn into a garden, however, they may in turn feed on healthy, ripening produce.

Prevention is the best control. Pick fruits and vegetables as they ripen and don't allow overripe or rotting produce to remain in your garden. The better able you can reduce fermenting smells that would draw picnic beetles to your garden, the less likely that you will have a problem with them.

Although you may temporarily be able to suppress picnic beetle numbers with insecticides, as long as fermenting smells are present they will continue to return. Also keep in mind that there is a waiting period between when you apply an insecticide to your garden and when you can harvest your produce (check the label for how many days you need to wait). During that time, picnic beetles often return before you have a chance to pick your fruits and vegetables.