is to move the female to a new location. Certain butterflies, after enticing the female, will pick her up and fly her away from the vicinity of potential males. In other insects, the males will release a pheromone in order to make their mate unattractive to other males or the pheromone masks her scent completely. Certain crickets will participate in a loud courtship until the female accepts his gesture and then it suddenly becomes silent. Some insects, prior to mating, will assume tandem positions to their mate or position themselves in a way to prevent other males from attempting to mate with that female. The male checkerspot butterfly has developed a clever method in order to attract and guard a mate. He will situate himself near an area that possesses valuable resources that the female needs. He will then drive away any males that come near and this will greatly increase his chances of copulation with any female that comes to that area. In post-copulatory mate-guarding males are trying to prevent other males from mating with the female that they have mated with already. For example, male millipedes in Costa Rica will ride on the back of their mate letting the other males know that she's taken. Japanese beetles will assume a tandem position to the female after copulation. This can last up to several hours allowing him to ward off any rival males giving his sperm a high chance to fertilize that female's egg. These, and other, types of methods have the male playing defense by protecting his mate. Elephant seals are known to engage in bloody battles in order to retain their title as dominant male so that they are able to mate with all the females in their community. Copulatory plugs are frequently observed in insects, reptiles, some mammals, and spiders. Copulatory plugs are inserted immediately after a male copulates with a female, which reduce the possibility of fertilization by subsequent copulations from another male, by physically blocking the transfer of sperm. Bumblebee mating plugs, in addition to providing a physical barrier to further copulations, contain linoleic acid, which reduces re-mating tendencies of females. A species of Sonoran desert Drosophila, Drosophila mettleri, uses copulatory plugs to enable males to control the sperm reserve space females have available. This behavior ensures males with higher mating success at the expense of female control of sperm (sperm selection). Similarly, Drosophila