Shy Red Caterpillar

I don't really think this caterpillar (a less-typical color morph of Helicoverpa zea?) is hiding very well in that Texas ranger bud; it's got it's head in there eating the tender flower parts with its red posterior advertising to the world: Well-Fed, Juicy Caterpillar Here. Corn earworms usually come in greens although I've seen them (or H. virescens, geranium budworm) take on a reddish color when they are feeding on the red or pink geranium flowers. However, why would this caterpillar crypti-color red against the grey of the leucophyllum? The half-ripe wood of this plant is red/brown; maybe the caterpillar spent time on those stems and so became the red color. Or it is not Helicoverpa at all.