Non-reproductive aggregations of insects, such as the gregarious overwintering of monarch butterflies at specific sites in Mexico and California (see Plate 3.5, facing here), are social interactions. Many tropical butterflies form roosting aggregations, particularly in aposematic species (distasteful and with warning signals including color and/or odor). Aposematic phytophagous insects often form conspicuous feeding aggregations, sometimes using pheromones to lure conspecific individuals to a favorable site (section 4.3.2). A solitary aposematic insect runs a greater risk of being encountered by a naïve predator (and being eaten by it) than if it is a member of a conspicuous group. Belonging to a conspicuous social grouping, either of the same or several species, provides benefits by the sharing of protective warning coloration and the education of local predators.