# Innate Nectar Plant Attraction Is Primarily Visually‐Guided but Olfactory‐Stimulated in North American Monarch Butterflies

## TL;DR

Monarch butterflies are naturally drawn to a nectar plant mainly through sight, but smell enhances this attraction.

## Contribution

A nonforced choice assay reveals innate attraction to Lantana camara in monarch butterflies.

## Key findings

- Monarch butterflies show innate attraction to Lantana camara using visual cues.
- Olfactory cues enhance the effectiveness of visual attraction in butterflies.
- The specific visual or olfactory cues responsible remain unidentified.

## Abstract

In flower‐visiting insects, innate sensory preferences facilitate efficient foraging strategies in complex natural environments. Here we describe a nonforced choice assay to investigate innate attraction to a common nectar resource (
Lantana camara
) in naïve monarch butterflies (
Danaus plexippus
). We find that monarch butterflies have an innate attraction to
L. camara
in our assay. Visual cues are necessary and sufficient for sustained attraction at the tested range. However, olfactory cues increase the salience of visual cues for sustained attraction. The identities of the specific attractive visual or olfactory cues are not resolved. Altogether, this simple nonforced choice assay is suited to reveal quantitative differences in innate attraction in monarchs and, presumably, other insects.

In flower‐visiting insects, innate preferences facilitate efficient foraging strategies in complex natural environments. We find that naïve monarch butterflies (
Danaus plexippus
) have an innate attraction to the nectar plant
Lantana camara
that primarily utilizes visual cues but is enhanced by olfactory cues.