Drawn to a flame

This exercise is a part of Educator Guide: Ant Ecosystem Disruption and Insects to Light / View Guide
Multiple images of a yellow brimstone butterfly are shown via motion capture. The insect is flying in circles, with its back pointing toward an illuminated tube light inside a flight arena at Imperial College London.
A brimstone butterfly (Gonepteryx rhamni), shown in multiple locations using motion capture, tries to keep its back toward a tube light as it orbits it inside a laboratory at Imperial College London. This abnormal flight behavior around artificial light may make the insect lose its sense of direction.Thomas Angus

Directions for teachers:

To engage students before reading the article, have them answer the “Before Reading” questions as a warmup in class. Then, instruct students to read the online Science News article “Insects flocking to artificial lights may not know which way is up” and answer the “During Reading” questions. As an optional extension, instruct students to answer “After Reading” questions as a class discussion or as homework.

This article also appears in the February 24 issue of Science News. Science News Explores offers another version of the same article written at a middle-school reading level. Post this set of questions without answers for your students using this link.

Directions for students:

Answer the first set of questions as instructed by your teacher before reading the article. Then, read the online Science News article “Insects flocking to artificial lights may not know which way is up” and answer the remaining questions as directed by your teacher.

Before Reading

1. What do you observe about insect behavior at night when a light is turned on? What is a possible reason for this behavior? In one sentence, provide a possible theory.

Student answers will vary, but may say insects appear to be drawn to the light. A theory could be that they are attracted to the light because it is a heat source.

2. Imagine two moths flying around a lamp at night. Sketch a picture of the moths and lamp. Include in your sketch the orientation of the moth srelative to the lamp. In other words, are they facing toward the light, away from it or one in each direction?

Answers will vary, but the image should clearly show the moth’s orientation relative to the light.

3. Watch the video embedded in the Science News article. What do you observe about the orientation of the moths’ bodies to the light bulb? Was your original prediction from question 2 correct? What could this behavior tell you about the effects of artificial light on the moths? Explain.

When flying around the bulb, some moths appear to orient themselves with their backs toward the lightbulb. Others turn in circles and dive toward the ground or fly straight up.

During Reading

1. What does new data suggest about why certain insects appear “captivated” by light?

New data suggests insects lose their sense of up and down.

2. Describe one of the previous hypotheses regarding the behavior of flying insects around a nighttime light source.

There are three possible answers. (1) Light blinds the insects, trapping them near the light. (2) Insects see the light as a safe place to fly. (3) Insects mistake the light for the moon, which they could use for navigation.

3. Describe how insects naturally orient themselves relative to a light source according to this new study.

This new study indicates insects will naturally turn their backs to the light.

4. What advantage would this orientation provide to an insect flying in sunlight?

In sunlight, insects turn their backs to the light, which orients their feet toward the ground.

5.  What is an entomologist? Give an example of one from the article and explain how your example fits the definition.

An entomologist is a scientist who studies insects. Samuel Fabian was an entomologist in the study described in the article. He and his colleagues used cameras to track insect behavior around artificial lights.

6.  List two types of equipment used in this study.

Answers could include hanging lights, standing lights, a high-speed infrared camera, a white sheet, artificial lights or any other equipment mentioned in the article.

7. Surprising scientific findings often lead to more questions. What is one question that scientists now have as a result of the findings in this article?

Answers will be one of the following two options. (1) Do insects from different latitudes have different sensitivities to light pollution? (2) Can outdoor lights be altered to make them less attractive to flying insects?

After Reading

1. How important is it for a flying insect to gauge their location relative to the ground, such as how high they’re flying or whether they are facing upward or downward? Is accuracy important, somewhat important, or unnecessary? Explain your answer.

Answers will vary.

2. This study found that the light affected fruit flies less strongly than moths and dragonflies. Read through this article and find a potential reason for this difference. Explain your theory, being sure to describe how this reason could contribute to differences in light sensitivity.

Answers will vary, but many students will likely point to the fact that fruit flies are better at flying in the dark than moths and dragonflies. Students may go on to explain that this may mean fruit flies rely upon other senses or strategies for determining their orientation in 3-dimensional space.