Why Do Insects Follow Scent Trails to Flowers?

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Why do insects follow scent trails to flowers? Floral scent is a cue that helps an insect find a flower before any colour or shape comes into view, and it changes how hard the insect works to forage. Research on hawkmoths, butterflies and plant bugs describes this role. This article explains the mechanism using three research papers and separates what they establish from what they leave open. For related plant defence and signalling, see how plants defend against insect herbivores and how plants recognize pathogen molecules.

Quick answer

• Scent works alongside sight. The butterfly study notes that “Besides visual information such as colour and shape, floral scents are another crucial cue for flower visitors”.
• Scent makes a flower easier to find. The hawkmoth study reports that floral scent works “not only by increasing detectability but also by enhancing the pollinator’s foraging efforts”.
• Insects can steer toward scent. The hawkmoth study describes flight tracks “color-coded regarding the upwind speed of the moth”.
• Scent can be enough on its own. For plant bugs, the bagged-flower test showed that “olfactory cues are sufficient for them to locate their host”.

How we chose

This article uses the three research papers named at the end: a 2015 butterfly study, a 2016 hawkmoth study and a 2016 plant bug study. Each factual sentence below is tied to a quote from one of them.

Why scent matters to a flower visitor

Insects find flowers with several cues at once. The butterfly study states that “Besides visual information such as colour and shape, floral scents are another crucial cue for flower visitors”. The same study notes that “Hymenopterans can detect and learn a wide range of floral volatiles from various plant species.” Scent is therefore part of a larger set of signals rather than a stand-alone system.

The balance between scent and sight depends on the insect’s time of activity. The butterfly study states that “In general, diurnal butterflies and hawkmoths rely on visual cues over olfactory ones when foraging, whereas the opposite is true of nocturnal moths.” A day-flying butterfly may lean more on colour, while a night-flying moth may lean more on smell.

The same butterfly study describes a weaker role for scent in day-flying insects. It says that “In diurnal Lepidoptera, floral scents may play a lesser but still important role in triggering searching behaviour, or in attraction at close range.”

How scent raises a flower’s pull

The hawkmoth study tested whether scent helps individual flowers, not only whole plants. Its key finding is that “floral scent functions to increase the fitness of individual flowers not only by increasing detectability but also by enhancing the pollinator’s foraging efforts.” Two effects are named here: a flower becomes easier to detect, and the pollinator is pushed to work harder on it.

The study reports the wider context in similar terms. It states that “Floral scent not only attracts pollinators”, and that the authors wanted to show that “floral scent increases the fitness of individual flowers not only by increasing their detectability”. The point is that scent is linked to the flower’s reproductive success, not only to the insect’s arrival.

The study also places scent in a long research history. It notes that “Floral scent has been associated with insect pollination since the 18 th century”, and that its complex functions “have been only recently investigated in more detail, due to the availability of new molecular and analytical techniques.”

Following the scent in flight

The hawkmoth study used flight tracks to show how a moth moves toward scent. Its figure caption reads “Flight tracks are color-coded regarding the upwind speed of the moth.” The text then reports that “The analyses revealed a tendency for a higher upwind speed towards EV flowers emitting BA”, where EV and BA refer to the flowers and scent compound tested in the study. This is evidence that the moths moved faster into the wind toward the scented flowers.

The study reports a tendency, not a fixed rule, so the result describes the moths and plants that were tested.

Scent as a host-finding cue

The plant bug study tested a different insect group. The authors state that “To date, nothing is known about the cues these insect visitors use to locate the inflorescences and whether or to what extent floral scents play a role.” The study set out to answer that question with bagged and unbagged flowers.

The result shows that scent alone can guide these insects. The study reports that “Bagged inflorescences as well as natural scent samples attracted similar numbers of plant bugs as the non-bagged inflorescences, showing that olfactory cues are sufficient for them to locate their host.” The bags blocked visual cues, so the insects were responding to smell.

The study then identifies a compound. It reports that “Cis -jasmone was the major component within the inflorescence scent bouquet.” Its field tests found that “In two-choice field bioassays, this compound proved to be highly attractive to Neella , and thus obviously plays a key role in finding host plants.” The result is specific to that system.

Colour and scent together

Scent can change how an insect weighs colour. The butterfly study reports that “When scent from essential oils of either orange flower or lily was introduced to the room, females’ tendency to select the red disc increased.” Scent therefore shifted the choice between colours in those females.

The effect differed by sex. The study notes that “In males, however, all plant scents were less effective than in females, such that blue was always the most favoured colour.” So the same scent did not change the choice in both sexes in the same way.

The butterfly study also reports that scent from a plant that is not in flower can change the choice. It states that “the odour of the non-flowering larval host plant, Citrus unshiu , shifted the preference to green in females.” The finding shows that odour alone can change an innate colour preference, even when the plant is not offering flowers.

What the research shows about the scent trail

Put together, the three papers describe scent as a cue that raises a flower’s pull, guides flight toward the source, and in some insects can outweigh sight. In the hawkmoth study, scent made individual flowers more attractive. In the plant bug study, scent by itself was enough to find a host. In the butterfly study, scent shifted colour choice in some insects.

The quoted passages above describe odour reaching an insect from a source, and the insect’s response to it.

What we could not verify

The three papers study specific systems: swallowtail butterflies, hawkmoths on Nicotiana attenuata flowers, and plant bugs on an Araceae inflorescence. Each result is tied to those species and conditions. The sources do not test every insect group, and this article does not claim that every flower-visiting insect follows scent in the same way.

What the sources do not say

The sources do not describe how long a scent trail persists after an insect passes, and this article does not state a duration. They also do not compare scent-following across all insect orders. They do not give any advice on planting scented flowers, and this article does not add any.

Frequently asked questions

Do insects find flowers by smell or by colour?

Both, depending on the insect. The butterfly study states that “In general, diurnal butterflies and hawkmoths rely on visual cues over olfactory ones when foraging, whereas the opposite is true of nocturnal moths.”

Can scent alone lead an insect to a plant?

In the plant bug study, yes. The study reports that “olfactory cues are sufficient for them to locate their host.”

Does scent make a flower more attractive?

The hawkmoth study reports that scent “enhancing the pollinator’s foraging efforts” and increases detectability, which together raise a flower’s pull.

Which compound was identified in the plant bug study?

The study reports that “Cis -jasmone was the major component within the inflorescence scent bouquet.”

Does scent change which colour an insect picks?

In the butterfly study, scent increased females’ tendency to select the red disc. The study notes that “all plant scents were less effective than in females” in males.

Sources

• “Plant scents modify innate colour preference in foraging swallowtail butterflies.” Biology Letters, 2015, doi:10.1098/rsbl.2015.0390. https://pmc.ncbi.nlm.nih.gov/articles/PMC4528451/ (opened 2026-10-28, HTTP 200)
• “Hawkmoths evaluate scenting flowers with the tip of their proboscis.” eLife, 2016, doi:10.7554/eLife.15039. https://pmc.ncbi.nlm.nih.gov/articles/PMC4884077/ (opened 2026-10-28, HTTP 200)
• “Nocturnal Plant Bugs Use cis-Jasmone to Locate Inflorescences of an Araceae as Feeding and Mating Site.” Journal of Chemical Ecology, 2016, doi:10.1007/s10886-016-0688-9. https://pmc.ncbi.nlm.nih.gov/articles/PMC4867150/ (opened 2026-10-28, HTTP 200)