They only lay one egg at a time, but they can lay many in a single day. I have no way of knowing how many eggs wild females lay. The average is about , but this varies from year to year. They lay fewer in hot, dry summers. Adult monarchs live for anywhere from 2 to 6 weeks, and females lay eggs and males mate throughout most of this period.
They use a combination of visual and chemical cues to find milkweed. Once they land on a plant, they use sensory organs on their feet and heads to tell them if it is a milkweed, and probably the quality of the milkweed. Females will wait a long time to find milkweed.
Sometimes in our cages we keep mated females without milkweed, and VERY rarely, we will find a few eggs on other plants or the sponges we use to feed the females. The caterpillars then die. We have done studies here at the University of Minnesota of females that were overwintering in Mexico.
The studies have shown that having milkweed around actually speeds up egg development. In some butterfly species you can see these testes from the outside, but not monarchs. At no time between egg fertilization and death do all body parts break down. Many of the features unique to the adult—such as the wings, eyes, internal reproductive organs, and long antennae—are actually present as tiny clusters of cells even in the egg.
These cell clusters grow and differentiate throughout the larval stage. During the pupa stage, they rearrange and develop further. For example, the adult compound eye forms from cells that were behind the larval eyes. Some body parts, especially muscles, degenerate at the end of the larval stage and are replaced by new muscles that allow the new kinds of movements associated with the adult stage. Larvae move very differently than adults, and thus most of their muscles are completely broken down by enzymes early during the pupa stage.
These broken down muscles do form a liquid within the developing pupa. I try to video the whole cycle. I notice that, during the first week of a chrysalid, it looks like it is empty, except at the top. This is why I have always wondered if the skin, itself, of the chrysalid, plays a significant role in the formation of the wings and other organs.
It takes 3 to 8 days for an egg to develop. Then the caterpillar larva hatches, and grows for about 15 days. After that comes the pupal chrysalis stage. Monarchs born in Canada have completed their life cycle and now a second generation of butterflies appears.
I am not trying to argue. So, I ask you this, if the Monarchs are endangered, why wouldnt we want every single one to have the best chance possible? I look forward to learning more here. Thank you for your patience and answers. View Larger Image. When the weather changes, you can release them to wind.
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Keith November 17, at pm - Reply. Leave A Comment Cancel reply Comment. Go to Top. Just after they have molted, their tentacles will look droopy, and you may see the old skin behind the larva. They will usually eat this skin! As larvae grow, so will their appetites. Be sure to check their leaf supply regularly.
If you started with a small container, you will need to move the larvae to a larger one for adequate food supply and with enough room for the adult butterflies to emerge from the chrysalis. This should be done during the fourth instar, when the larvae are about an inch long.
Be sure the upper surface is flat for easy attachment for pupating. Many types of containers can be used; clear or screen sides make it easier for students to see the Monarchs. Examples of good rearing containers include jars or cups with lids with holes, or covered with netting held on with a rubber-band.
Ice cream buckets with a net rubber-banded over the top also work well, as do aquaria with screen tops. Feel free to use your imagination! There is some mortality in the larval stage. One bacterial disease causes the larvae to turn very dark, and then die.
Others may simply stop eating and growing, and then die after for several days. While this may be difficult for the students to accept, you can assure them that as long as they have been keeping the containers clean, it is not their fault.
Remove dead larvae and clean their containers well to prevent the spread of disease. When larvae are ready to pupate, they crawl to the top of their cage, attach themselves with silken thread, and form a prepupal "J" before shedding their skin for the last time. This process is fun to watch but it happens quickly. You can tell that they will shed their larval skin soon within minutes when their tentacles hang very limply and their bodies straighten out a little.
If desired, you can move the pupa after it has formed. Wait until it is hard and dry several hours or longer. Tie a piece of thread around the cremaster and with a needle or pin carefully tease away the silk that is holding the pupa to the surface.
Leave the silk attached so the thread does not slip off see figure below. If the pupa has fallen and there is very little silk remaining, add a drop of glue to the thread where it surrounds the cremaster. The loose ends of thread can then be tied through a hole in the container cover or through a space in the netting.
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