You may not have seen many monarch butterflies yet this season, but the odds are good that the numbers will increase dramatically over the next several weeks.
This is because the female monarchs have been quietly busy laying eggs on the milkweed locally and much further north. Probably less than 10% of those eggs will successfully make it to adulthood, but that is still 10 to 20 adults per laying female.
Between the migrants from the north that will peak in abundance around August 29th to September 10th and the local population increase, numbers should be high in the next several weeks.
Try Your Hand at Raising Monarchs?
Although it is late in the season there is still time to experience the wonderful transformation of monarch caterpillars into adult butterflies by rearing one in a container. It is a natural miracle that is worth the time and effort to see up close.
There are many guides for rearing monarchs online, but the process is simple – find a caterpillar, keep it clean and fed in a suitable container until it pupates, and let it go when it emerges as a butterfly.
While the steps are simple, there are few things to keep in mind.
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Try to collect only healthy-looking larger caterpillars. They will need less care and are less likely to die from disease or parasites.
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Avoid touching the caterpillar or pupa.
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The container should be well ventilated, kept clean and out of direct sunlight. A clear 16 oz. deli container with lid and a few small holes in it works well (or an ice cream pail with lid)
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Remove frass (caterpillar poop) at least once a day and ensure there is always fresh milkweed for food. Use the same kind of milkweed that you found it on.
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If there is condensation on the inside of the container, it should be removed and figure out why. Caterpillar frass is wet and too much food could cause a problem.
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When the caterpillar is ready to pupate, it will usually go to the top of the container, spin a button of silk, and hang upside down in a J shape. Pupation is usually only a few hours later.
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Allow the green pupa to rest for a day and then add a small stick or tape a piece of yarn on the inside of the container. (This is to assure that the newly eclosed (emerged) butterfly with soft, wet wings has a way to climb up if it falls). The wings have to hang straight while they dry and harden.
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When the pupa gets dark and you can see the wings through the skin – in about 9-14 days after pupation – it will be a short time before the monarch ecloses (usually in the morning).
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After the wings are dry – about 5 hours – let the butterfly go.
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Note that not all rearing will be successful. Monarch caterpillars can get sick or may have parasites that are not obvious when they are collected.
Here are links with detailed information:
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Rearing Monarchs (loudounwildlife.org)
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SaveOurMonarchs.org (Chanhassen, MN)
Right now I have almost 2 dozen monarch caterpillars and pupae in rearing containers just from collecting them along Cty Rd K next to our house for about 2 weeks. I have caterpillars and pupae that will be going to the Rassbach Museum for their monarch display.
Also locally, I’ve been doing presentations for Nathan McMahon’s classes at Menomonie High School for several years and expect to do so again this fall during peak monarch migration (Aug 29th to Sep 10th).
In the research realm I’ve been participating in monarch research with both Monarch Watch and the Monarch Health Project at UG-Athens for over 10 years. In that time I’ve learned a lot of things about how to successfully rear monachs and help support the ecosystems that they depend on.
Richard D. Breen is a retired Analytical Chemist and citizen scientist contributing to several monarch related projects. He lives in the rural Menomonie area and may be contacted at [email protected]
