Three Monarch Caterpillars munching on a milkweed at the Garland Community Garden - April 25, 2015
Journey North reported that Monarch butterflies left their roosts in Michoacán, Mexico, on March 24 in what is one of their latest departure on record. It's a good thing though, as the Milkweeds, at least in North Texas, are for the most part barely substantial to support the caterpillars in this important first stage of their journey. The milkweed is the only plant on which the Monarch butterfly will lay its eggs.
At the Garland Community Garden we have two puny Tropical Milkweeds which I noticed yesterday are now host to no less than seven Monarch Caterpillars. I know there is a certain school of thought who say the tropical milkweeds are not good and the people should not grow them, but I can tell you for a fact that if the Monarchs had to depend on the tiny two inch native Texas Green milkweeds in our community garden today, they would be sorely out of luck.
It takes about six weeks for Monarch to develop from an egg into a butterfly. The ones shown in the photo above from the Garland Community Garden have about another month to go. They should be butterflies about the second or third week in May. However, survival rates are low. Only about 5% survive to become fifth instars. The others are killed by a variety of predators, including ants, spiders, true bugs, beetles, and lacewing larvae.
LIFECYCLE OF A MONARCH BUTTERFLY
1. Life for the monarch begins as an egg, laid underneath a milkweed leaf.
Three to five days later . . .
2. That egg hatches into a first instar larva (caterpillar).
Over 9 to 15 days . . .
[Larva (caterpillar) increases its body mass by about 2000 times as it molts and shedding ti skin five times to allow for this increase in size. The period between each molt is called an 'instar".]
At about two weeks or 15 days. . .
3. Caterpillar pupates. They form a shell called a chrysalis or pupa.
Nine to fourteen days later. . .
4. Adult butterfly emerges from the pupa casing, pumps fluid from its abdomen into its wings and flies off to nectar, mate and if a female to lay eggs.
Adult butterflies that don't migrate live another 2 to 6 weeks.
More detail on Monarchs can be found HERE.
ADDENDUM TO THIS POST
Yesterday (Sunday April 26) I returned to look at the Monarch catepillars. They have eaten all the leaves from both milkweed plants which were only about 15 inches high. When I saw them they were munching on the stems. I don't think the caterpillars are large enough to form pupas so my guess is they will die. I'll report on Tuesday with an update. I've called all my friends and no one has plants any taller than few inch seedlings.
I wonder if, due to our cold wet spring and the late arrival of the milkweed if we will experience a loss in the Monarch population as we did a couple of years ago.
The photo below was taken at dusk of the same day the photo at the beginning of this article was taken. All the leaves are gone. In the bottom left you can see a caterpillar munching on a stem. Notice all the green leaves in the bottom of the photo above. These are milkweed leaves. By the time I saw them in the morning they had already defoliated the top part of the plant. By evening of that same day they had defoliated the entire plant--in the space of about six hours.