Name_________________
Shooting the Poop
Featured scientist: Martha Weiss from Georgetown University
Research Background:
Imagine walking through a deciduous forest in the middle of summer. You can hear birds
chirping, a slight breeze rustling the leaves, and a faint pinging noise like rain. However, what
you hear is not rain – it is the sound of millions of forest insects defecating!
Forest insects, like caterpillars, are a great source of food for many species. As such,
caterpillars have many defense strategies to protect themselves and evade predators, including
camouflage to avoid detection, nasty defensive chemicals and bright colors to warn predators to
stay away, or even building shelters out of plant leaves to
hide in. The smell of frass (insect poop) alerts predators
that a tasty insect is in the area, so usually insects keep
moving and leave their frass behind. But what if the insect
relies on a shelter for protection and cannot keep moving
away from its home?
The forest insect, Epargyreus clarus (the silver-spotted
skipper) has a variety of defense strategies against
enemies, including building leaf shelters for protection.
While raising E. clarus caterpillars in the lab, a scientist
noticed that E. clarus made a pinging noise in their
containers. Upon further observation, it was discovered
that they “shoot their poop”, sometimes launching their
frass over 1.5m! The scientist wanted to determine why
these caterpillars might engage in this very strange
behavior. Perhaps flinging their poop is a defensive
strategy to avoid predator detection.
To evaluate whether the smell of frass alerts predators to
the presence of a caterpillar, the scientist Weiss
conducted an experiment with the predatory wasp
Polistes fuscatus. She allowed two E. clarus larvae to
build shelters on a leaf and then carefully removed the
larvae. She then inserted 6 frass pellets into one of the
shelters, and 6 beads designed to look like frass but with
no smell (control treatment) into the other. She placed the
leaf in a cage containing an actively foraging wasp colony
(n = 10 wasps), and recorded how many times the wasps
visited each shelter (control or frass), and how much time
the wasps spent exploring each shelter.
A silver-spotted skipper caterpillar
building its shelter by rolling a leaf
The completed shelter
A predatory wasp visits a shelter with
caterpillar frass present.
Data Nuggets developed by Michigan State University fellows in the NSF BEACON and GK-12 programs
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Name_________________
Scientific Question: Does flinging its poop help Epargyreus clarus avoid predator
detection?
What is the hypothesis? Find the hypothesis in the Research Background and underline
it. A hypothesis is a proposed explanation for an observation, which can then be tested
with experimentation or other types of studies.
Scientific Data:
Use the data below to answer the scientific question:
Shelters
containing
beads
Shelters
containing
frass
% Visits
(Mean ± SE)
30.3 ± 3.07
69.7 ± 3.07
% Time spent on
shelter and its leaf
(Mean ± SE)
21.4± 3.8
78.6 ± 3.8
The data table shows the response of Polistes fuscatus foragers (n =10 wasps) to shelters containing
frass pellets or glass beads.
What data will you graph to answer the question?
Predictor variable:
Response variables: (a)
(b)
Data Nuggets developed by Michigan State University fellows in the NSF BEACON and GK-12 programs
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Name_________________
Below is a graph of the data:
Interpret the data: Based on this evidence, write a statement that helps answer the
scientific question. Connect the pattern in the data to a pattern in the natural world.
Justify your reasoning using data.
Data Nuggets developed by Michigan State University fellows in the NSF BEACON and GK-12 programs
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Name_________________
Your next step as a scientist: Science is an ongoing process. Did this study fully answer
your original question? What new questions do you think should be investigated? What
future data should be collected to answer them?
Data Nuggets developed by Michigan State University fellows in the NSF BEACON and GK-12 programs
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