Monarch Butterfly (Danaus plexippus)


Class: Insecta
Order: Lepidoptera
Family:    Danaidae
Size:    Body: 1 inch (2.5 cm) Wingspan: 3 inches (7.5 cm)
Weight: Unknown
Diet: Adults eat nectar from flowers, caterpillars feed on milkweed plants
Distribution: North and South America, New Zealand and Australia
Young:  Up to 400 eggs per fertilization
Animal Predators:  Stink bugs, ambush bugs, wasps, mice and birds
IUCN Status: No special status
Terms: Young: Caterpillar  Group: Rabble
Lifespan: 2 to 6 weeks; 7 months or more if they hibernate



·         The monarch butterfly is the state insect of Illinois, Alabama, Delaware, Idaho, Texas, West Virginia and Minnesota.

·         The monarch is featured on a 45-cent Canada stamp. 

·         In 1995, three areas in southern Ontario, Canada, were designated as monarch butterfly reserves: Point Pelee, Long Point and Prince Edward Point. 



Monarchs’ wings have tiny veins running through them, which give strength to them, enabling flight. The scales on the wings are made of chitin, and the colours of the scales help predators to distinguish monarchs from other butterflies so they can avoid them because of their bad taste. This defence is acquired during their caterpillar state, from eating the toxic plant milkweed, and is stored until the monarchs are adults. Warning colouration may work particularly well in adult butterflies because the hard body and wings allow a predator to bite the adult, taste the poison and release the butterfly without killing it. The adult monarch has bright orange wings with black veins and a wide border containing two rows of white spots. Males and females are easily distinguished from each other by the two highly visible black spots—which are scent glands—on the male’s hind wings and the thinner black webbing on the wings. Monarch larvae or caterpillars are striped yellow, black and white; they grow to about two inches (5 cm) in length.  



Unlike many other butterflies, monarchs do not hibernate, but migrate south in great numbers each fall and return to the same area the following spring. The trip south can be more than 2,500 miles and many of the butterflies do not survive the journey to reach a warmer place, such as California or Mexico. While in the south, the butterflies go into a state of almost complete inactivity, only flying on the warmest of days.


Feeding Habits

Monarch butterfly larvae feed on a wide range of milkweeds of the genus Asclepias. In their butterfly state, monarchs sip nectar from flowers. 



Monarchs go through four stages of life: egg, larva (caterpillar), pupa (cocoon), and adult. The pale green ribbed egg is laid on the underside of milkweed plant leaves and stems. The egg stage lasts from four to 10 days and is followed by a stage in which it becomes a caterpillar that needs to feed on the milkweed in order to survive. The caterpillar sheds its skin up to four times before reaching its full-grown state of two inches. It then spins itself up into a beautiful green cocoon and will emerge in 10 to 12 days as a beautiful orange-and-black adult butterfly. The entire process takes approximately four weeks. When monarchs emerge from the cocoon, their wings are crumpled and wet. Monarchs are only able to mate in their final stage and live two to six weeks, or even seven months or more if they wait to mate until the next spring, after the migration season.  



Monarchs have difficulty flying in temperatures under 55o F (12.7oC), and use the dark colours in their wings to soak up sunrays until the butterfly has reached the right temperature in order to be able to fly. Monarchs, like birds, follow patterns of seasonal migration. There are two distinct populations in North America, those that breed in the east and those that breed in the west. Each autumn, the eastern population flies to the volcanic mountains of eastern Michoacan in central Mexico while the western breeders spend their winters along the California coast. The mass of butterflies breaks up in March and early April and the monarchs begin their migration north. It takes several generations of butterflies to reach the northern part of the range, each generation responding to the availability of milkweed plants. 



In their caterpillar state, monarchs are completely dependent on the milkweed plant. Pesticides to eliminate this toxic plant have led monarchs to become listed as Special Concern in Canada by Environment Canada’s COSEWIC Endangered Species List. Steps are being undertaken to educate people about the necessity of the milkweed to the ecosystem.



Monarch Butterfly Wildlife Fact File, IM Pub, US