Avoiding Diapause > Healthy Host Plant
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.
This is a photo of a cottonwood sucker leaf. The main tree sent up new growth in the middle of summer creating this healthy, thick, gargantuan-sized leaf. (Note the size of a mature fifth instar red spotted purple caterpillar for comparison). Feeding Limenitis caterpillars healthy host isn't the triggering mechanism to avoid diapause (long day photoperiod is); however, it's always a good idea to feed your caterpillars healthy host plant. For some species groups, healthy host plant is the triggering mechanism for caterpillars allowing them to avoid hibernation and providing you an opportunity to get a reared adult sooner rather than later.
By switching Papilio indra minori natural host Lomatium junceum with lab host Lomatium graveolens, you provide a double benefit. First, Lomatium graveolens happens to be more accessible to Northern Utah folks who raise Papilio indra minori. The second, and most important, value of this plant is that it grows in the tops of the Wasatch Mountains and is more succulent than L. junceum. When caterpillars feed on healthy sprigs of this plant, it seems stimulate their pupae to NOT diapause as they perceive that somehow their 'natural' host is extremely succulent and healthy, encouraging a natural subsequent flight of P. indra minori. In other words, their pupae do not diapause; but an adult butterfly emerges immediately.