Blister beetles are extremely varied in appearance. In fact, they don't all even belong to the same genus, but the one thing they have in common is that they all excrete cantharidin from their joints. It's this cantharidin which is the active ingredient in the infamous aphrodisiac known as Spanish fly. The actual Spanish fly is a variety of blister beetle which is emerald-green and it belongs to the genus Lytta. The Iron Cross Blister Beetle, on the other hand, is red, black, and yellow, and it belongs to the genus Tegrodera. Recently the desert southwest has seen millions of these little bugs crawling all over the place. Here in Trona the beetles seemed particularly attracted to broad-leaved gilia (Gilia latifolia), whereas elsewhere different plants such as desert woolly star (Eriastrum eremicum), for instance, seemed to be their preferred food source.