Predicted proportion reduction in population size in monarch butterflies caused by intraspecific density-dependent larval competition.

Mean (standard error) percent population reduction caused by intraspecific density-dependent larval competition in monarch butterflies using two different methods of calculating the predicted proportion reduction population size. The three measures of density incorporate different life-stages. Densities of eggs and larvae include all larval instars whereas large larvae include only 3rd, 4th and 5th instars. Data come from published field surveys of milkweed and monarch larvae [11], [25], [26] and are for the early phase of the breeding season in the South (see text).