Following mating, a female Monarch will be ready to begin ovipositing her eggs after only several hours. She travels from leaf to leaf and plant to plant, typically depositing no more than one egg per leaf and only one or two eggs per plant. It is thought that when the female lands on a leaf she is testing the plant for suitability with the sensors on her feet that are called tarsi. She curls her abdomen around, ovipositing a tiny golden drop that is no larger than a pinhead.
In the short video, in the second clip, you can she she ‘rejects,’ the leaf. She first tests it with her feet, then curls her abdomen, but does not leave an egg. In the third and last clip, success! She finds a leaf to her liking and leaves behind a single egg.
The female continues on her quest to find milkweed, possibly returning to the same plant, but more likely, she will go on to the next patch of milkweed. In the wild, female Monarchs deposit on average between 300 to 500 eggs during her lifetime.
It’s a very different story for Monarchs that are captive bred. The attendant will walk into the enclosure where the frantic males and females are kept, with a handful of milkweed leaves. The female is so desperate to oviposit her eggs, she will dump a whole load on one leaf, without even testing it with her feet. I have observed this behavior at breeding locations and it is really quite disturbing, knowing how wholly unnatural it is for Monarchs to deposit eggs in large clusters.
Four reasons to stop mass breeding and rearing:
- Mass production of Monarchs makes it easy to transmit disease.
- More virulent strains of pathogens are spreading to wild Monarchs.
- Reared Monarchs are smaller than wild Monarchs.
- A genetic consequence of breeding closely related individual Monarchs weakens the species.
The Xerces Society, Monarch Watch, Journey North, Monarch Joint Venture, and the petition to list Monarchs as an endangered species all recommend the following:
From the Xerces Society
Answers to a few frequently-asked-questions and answers about rearing
How can I rear Monarchs responsibly?
- Rear no more than ten Monarchs per year (whether by a single individual or family). This is the same number recommended in the original petition to list the monarch under the Federal Endangered Species Act.
- Collect immature Monarchs locally from the wild, heeding collection policies on public lands; never buy or ship monarchs.
- Raise Monarchs individually and keep rearing containers clean between individuals by using a 20% bleach solution to avoid spreading diseases or mold.
- Provide sufficient milkweed including adding fresh milkweed daily.
- Keep rearing containers out of direct sunlight and provide a moist (not wet) paper towel or sponge to provide sufficient, not excessive, moisture.
- Release Monarchs where they were collected and at appropriate times of year for your area.
- Check out Monarch Joint Venture’s newly updated handout, Rearing Monarchs: Why or Why Not?
- Participate in community science, including testing the Monarchs you raise for OE, tracking parasitism rates, and/or tagging adults before release.