I've noticed over the years that when I find a tobacco hornworm egg on a particular tobacco plant, that I am more likely to find one again on that plant or its immediate neighbor. Do they like this variety more than others? Is it a difference in ambient lighting at night? Are there other factors that cause these egg laying repeats?
From this study, it appears to be a learned preference. If laying an egg on a particular plant was a nice experience, then they return to the same plant the next time.
This study also raises in my mind the question of whether intentionally planting sacred Datura near a tobacco bed may draw hawkmoths (i.e. hornworms) away from my tobacco. Well, one look at a random, sacred Datura plant gave me the answer: a resounding, "Nope. Looks awful, and is too large."
Bob
From this study, it appears to be a learned preference. If laying an egg on a particular plant was a nice experience, then they return to the same plant the next time.
"...even a single egg-laying experience was sufficient to direct a moth's interest to the very plant on which an egg had previously been laid."
"Naïve moths, which had not previously laid an egg on a plant, showed an innate preference for the leaves of sacred datura."
Learning helps tobacco hawkmoths to select a nectar source and oviposition site more efficiently
Max Planck researchers have gained new insights into the learning ability of tobacco hawkmoths. In two recent publications, they report that learning odors does not only play a role in foraging, but that female moths are also influenced by previously learned odors when choosing a host plant to...
phys.org
This study also raises in my mind the question of whether intentionally planting sacred Datura near a tobacco bed may draw hawkmoths (i.e. hornworms) away from my tobacco. Well, one look at a random, sacred Datura plant gave me the answer: a resounding, "Nope. Looks awful, and is too large."
Bob