Butterfly Diary
My fascination in the life cycle of the butterfly began when I accidently scanned a newly hatched caterpillar on milkweed florets two summers ago. I didn't even realize what I had until months later when I was "cleaning up" the image in Photoshop and was working at actual pixel level. As often happens when photographing in the wild- surprizing creatures crawl or fall out of your specimen. However I didn't know that it was a monarch caterpillar until I connected another event the following summer. Last June I had scanned another batch of milkweed before going up to a race in Mt.Tremblant, Quebec for a week. My housesitter informed me that there was a monarch butterfly flying around the house while I was gone. So apparently the plants I had been scanning had eggs- or larve on them. Since the success of the monarch is so closely related to the milkweed plant I decided to include it in my pictorial study of 'Asclepias syriaca' (the common roadside milkweed).
Monarch Eggs
Collected and scanned on July 2 2004
I collected two eggs from adjacent mature milkweed plants on July 2 2004. They may or may not have been laid by the same mother. Monarch females lay only one egg- on the underside of a leaf -per plant. Other insects lay their eggs on the milkweed or feed on it. The mother monarch looks for 'clean' plants which are not supporting other insects. A monarch egg is ovular and stands upright with a slight 'peak' on the top. When magnified you'll notice that it has distinct vertical ridges. In the picture above you can see the faint shadow of the caterpillar. The egg stage is 4-6 days. The larval (caterpillar) stage is 2-3 weeks.
Note: photo of female laying her egg and the egg to the right are from educational sites.
Magnified view
Day 1
These caterpillars were both hatched by the morning of July 5. One appears to be one day older as it is twice the size of the smaller one. So, the big one is already two days old at the time I started photographing. The above picture was taken early in the day, the lower picture at the end of the day.
After hatching the tiny larva will eat its own egg casing. The larger of the two nearly doubled in size by the end of the day! I didn't observe the little guy eating the first day. See that dark thing to the left of its face? That's its 'face mask'- skin that it had just shed. But the big one ate larger and larger holes in the leaf. It munched for a few minutes, rested- then about two minutes later- pooped, rested maybe half an hour; then started eating again. It appeared to me that they continued to eat throughout the night.
On the first day of observation the younger hatchling was as long as the width of a pencil eraser (about one-quarter of an inch). The older one was nearly twice as long, getting fatter and fatter with every nosh. The monarch larvae is an exclusive eater, eating only milkweed leaves. There are many varieties of milkweed. Here, the variety 'Asclepias syriaca' was the host plant. All milkweeds contain a chemical which when ingested by larvae make them distasteful to predators such as birds. The chemical is then transferred to the adult butterfly, so the species continues to have a weapon against predatory creatures. day two