Butterflies – Monarch Butterfly – Danaus plexippus
The above image of a Male Monarch butterfly was taken at the Butterfly site of the Adirondack Park Interpretive Center.
The Monarch Butterfly is a member of the milkweed group of butterflies (Danainae) so-named because various milkweed plant species are host plants for the larvae (caterpillars). Its adult wingspan is about 10cm with males being slightly larger than females of the species. The two black spots seen in the center of the hind wing in the photo above are called androconia which are specialized wing scales secreting pheromones, a chemical attractant to the the female Monarch. Their presence or absence is the easiest way to tell the sexes apart.
The image below is of the female. Note, also, that in the female, the black wing veins are somewhat thicker than in the male.
The adult butterfly extracts nectar from flowers by extending its proboscis like a straw.Â When not being used, it is kept in a curled position.
The proboscis can also be used to ‘drink’ as the Monarch was doing on the banks of the Ottawa River when I lay down on the rocks to take its picture.
Following mating, the female deposits eggs on the leaves of milkweed plants and eventually the larvae (known as caterpillars) hatch and feed on the leaves of the milkweed plant.Â As they do so, they incorporate poisonous cardiac glycosides into their tissues and pass these chemicals right along through the chrysalis stage of development to the adult form.Â These naturally-formed chemicals do not hurt the larva or the butterfly but do make the caterpillar and the adult butterfly poisonous, or at least distasteful, to birds and other potential predators.
The Monarchs are primarily a North American species but have a presence in many other parts of the world including Australia and New Zealand and occasionally in Europe and the UK.
In North America, they display a migratory pattern which sees the species move back and forth between locations in Canada and Mexico each year. The ‘migration’ is not a matter of one butterfly flying all the way from Mexico to Canada and back but involves the first generation leaving Mexico and flying part way. Later generations in the same year eventually arrive in Canada with arrival times, especially in Eastern Canada, highly dependent on weather conditions along the way. These middle generations have life spans of about 2 months but the last generation, which heads back to overwintering sites starting each Fall, has a much longer lifespan needed to make the trip south, as well as to survive through until the re-start of the northward ‘migration’ pattern in February of March.
There are probably more books published about the Monarch Butterfly than any butterfly in the world – from infant level to scientific level and every level in between.Â I’ve even bought a few myself :-).
Amazon always carries plenty of them as do others like Barnes & Noble. Searching on EBay or taking a look at the shelves of your local bookstore might yield some surprising finds. There are new titles featuring butterflies as their subject showing up on a regular basis and, because of this, it is often possible to find some great discount bargains in this genre of writing.
A few examples of butterfly books, etc. from Amazon – some a bit more fun to read than a science journal :-).
For Field Guides, I use a variety of them since none seems to satisfy all of my needs. Both the Peterson Guide and the Audubon Guide are useful and I’ve used both. Haven’t purchased the National Wildlife Guide to Insects for myself yet but reviews appear positive. The Kaufmann Guide covers all of North America but doesn’t include any larval forms so that might be a limitation for some users.