Post Hibernation Strategies > Larvae
Butterfly caterpillars that overwinter generally at all stages including:
- Unfed first instar caterpillars
- Half-grown caterpillars (third or fourth instar caterpillars)
- Mature Last Instar Caterpillars (Caterpillars that will pupate in the spring)
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Unfed First Instars Speyeria spp.
Here is an example of Speyeria (fritillaries) unfed first instars. After the caterpillars overwinter, place them on fresh cuttings of violets or pansies. Other genera of butterflies that also winter as unfed first instars are Cercyonis and some Boloria spp. Note: Unfed first instars are difficult to overwinter because of how sensitive they are to desiccation and mold (lab problem).
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Half-Grown Caterpillars Euphydryas spp.
There are many species of brushfooted butterflies that overwinter as half-grown larvae. Included in those are the checkerspots of the genera Euphydryas, Chlosyne, Poladryas, and Thessalia. When brought out of hibernation, make sure you have fresh host plant to feed them. Also, with checkerspot caterpillars, it is critical that you properly separate larvae on the hostplant; so that they do not feed for an instar and then re-diapause. In other words rear them in a small container with only one or two larvae per container. If they sense too many sibling caterpillars and insufficient host in one container, they will re-hibernate as a defense mechanism against starvation.
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Mature Last Instar Caterpillars
Butterfly caterpillars of the genera Thorybes, Erynnis, Hesperopsis, and Everes amyntula--to name just a few that I am aware of--overwinter as mature last instar. What that means is that they feed to maturity before overwintering and then pupate in the spring; emerging soon thereafter. Obviously, these caterpillars require no host plant after winter.
