Harlequin beetle Gymnetis caseyi is a large, colorful scarab flower beetle. This listing is for larvae (the immature form).
Adults are at their yellowest when they are allowed to dry out in the air for a bit, but they tend to live longer if they are kept in fairly humid conditions and reflect a slightly more greenish coloration. This change in colors is a good gauge for whether you are keeping them at the right humidity setting.
(Adults are sometimes also sold on this site in the related products section, below.)
Photo is of the adult beetle. They reach about 3/4 of an inch as adults.
Available as ~L2 larvae at $8 each. These larvae are communal and can be kept together, making them one of the easiest colorful and decent sized beetles to keep.