A Monarch Butterfly is a spectacular frequent visitor to the gardens and conservation areas of Newton. It is hard to miss this large butterfly with its striking wing pattern and coloration. The bright orange and black markings are a warning to predators that this insect is poisonous. The larvae feed on milkweed plants, the toxic chemicals of which are passed on to the adult butterfly. In fact, this warning coloration is so effective that several other insects mimic it.
There are four stages in the life cycle of the monarch butterfly and it goes through four generations in one year. Over-wintering adults mate before spring migration northward and they lay eggs on milkweed plants. Caterpillars are brightly striped yellow, black and white. They feed on milkweed leaves for two weeks before pupation. A mature butterfly will emerge from the pupa after about two weeks and will live as an adult for two to eight weeks, during which time it feeds on flower nectar, mates and lays more eggs. The adult of the fourth generation of the year can survive up to nine months.It is this butterfly that makes the lengthy migration south to over-winter in Mexico. Unfortunately, illegal deforestation in the area where monarchs over-winter has led to a decline in their number. Here in the Northeast is another threat: The invasive black swallow-wort plant produces stimuli similar to milkweed, and larvae hatched from eggs laid on this plant are poisoned.