Butterfly Caterpillar Question, and Amazement, Really....

I work at a nursery speciallizing in native plants, and know the food sources for larval and adult butterflies, teach that always. I know the relationship between black swallowtails and parsely, dill, fennel, etc. And monarchs and milkweeds, always teach that to people. It’s my job, to teach those great relationships.

But, I still am amazed by the fact that a mama butterfly can find a tiny crop of new plants in our nursery crop, totally out of it’s normal environment, lay eggs, and have a great crop of babies to feed on it. These are tiny plants, yet the butterfies still recognise them as host plants, and come down from wherever and lay their eggs for their cats to hatch and feed.

It’s not like they have normal ecological clues; this is a plant nursery, grown in little plots, but, sure enough, those butterflies find that little bunch of plants, and lay their eggs, every year.

I wonder about it. And, hope some fine minds here can give me a good clue about how that happens. Have read some of Rupert Sheldrake’s Morphogenetic Field Theory, but up for good simple explaination from the SD.

pulls up a chair to await an answer

Butterflies can detect their host plants by smell - or rather, by detecting chemicals given off by the plants, using their antennae.
http://quasimodo.versailles.inra.fr/inapg/susprot/ovipos/Nurian/index.htm

I believe they may also use visual cues - my reason for saying this is that I’ve observed that cabbage white butterflies will investigate any plant with glaucous grey-green leaves - for example broad(fava) beans and thistles - not just cabbages, but they don’t stop and lay eggs on them.