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Monarch butterfly eggs
The eggs of the monarch butterfly (Danaus plexippus) are quite small - a hand lens is useful to see their details.
The eggs are laid singly and are about 1 mm high, weighing less than 0.5 mg1.
The outer layer of an insect eggshell has a protective layer known as the chorion2, which stops it from drying out3, but also allows gas exchange to occur4. This outer covering has a pattern of vertical and horizontal ridges.
There are small funnel-shaped openings at the top of the egg known as micropyles. These allow sperm to enter the egg so that it can be fertilised2.
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| Raising monarchs | Eggs | Caterpillars | Chrysalis | Butterflies |
References
1. Monarch (Danaus plexippus). iNaturalist NZ https://inaturalist.nz/taxa/48662-Danaus-plexippus.
2. Gullan, P. J. & Cranston, P. S. The insects: an outline of entomology. (Wiley-Blackwell, 2010).
3. Monarch Watch : Biology : Anatomy. https://monarchwatch.org/biology/index.htm.
4. Reproduction. The Monarch Joint Venture. https://www.monarchjointventure.org/monarch-biology/reproduction.
5. Moths and Butterflies of New Zealand Trust - Pūrerehua Aotearoa.