Most people who raise butterflies would like to witness the emergence of the adult butterfly sooner rather than later. However, one natural obstacle that delays immediate adult emergence is the diapause or hibernation of the ovum, larva, or pupa.
This can pose an inconvenience to lab rearing when you start raising a butterfly caterpillar one year; but have to wait one or more years to obtain adults. There are lab techniques that you can utilize to coax some species groups of butterflies to avoid diapause and produce healthy adult butterflies faster than in nature.
These techniques include exposing butterfly immatures to:
- Long day photophase (18+ hours of light)
- High Temperatures
- High humidity
- Very healthy hostplant (or hostplant with new growth)
Interestingly enough these stimuli that prevent butterfly immatures from entering diapause are the same triggers that cause these same immatures to break diapause after overwintering.
This simply is a technical term meaning to keep your room light on for 18 or more hours to expose eggs, caterpillars, or pupae to summer conditions; coaxing them to avoid hibernation.
High Humidity (1)Eggs, larvae, or pupae of some species groups will avoid diapause if exposed to timely high humidity. This is hopefully intutive because these conditions, in the right physiogeographic regions, promote new growth of larval host plants and adult nectar plants.
Always remember that, in the lab, raising caterpillars under high humid conditions isn't ever a good idea unless you're rearing Limenitis species or species from humid habitat. However, it is a good idea to expose multi-voltine pupae to intermittant mist spraying of water to encourage them to emerge.
There are some species of butterflies that normally only have one flight per year; unless the region where they fly (usually an arid or desert region) has sufficient or unusual levels of precipitation which triggers healthy new growth of its host plants.
When feeding caterpillars in the lab, you can simulate the responses to spring rains or summer monsoons by providing caterpillars with very succulent and/or healthy host plant.