Project Proposal: The Effect of Mint (Mentha piperita) on Habitat Choice in Pill Bugs (Armadillidium vulgare)

[Student’s name’s redacted]


Arthropods are common pests that can be abundant and bothersome inside the household. As such, many people seek out natural insect repellent that won’t be harmful to the environment. The mint plant is commonly suggested as an insect repellant by nonscientific sources and essential oil companies despite mixed evidence to support that claim (Cloyd, Keith, Kalscheur, & Kemp 2009; Koc, Oz, & Cetin 2012). This experiment seeks to test the validity of essential oil claims by investigating mint’s potential to deter pill bugs (Armadillidium vulgare).

Previous research supports the idea that arthropod behavior can be altered by external scents (Drahokoupilová & Tuf 2012). Drahokoupilová and Tuf (2012) investigated the effects of external marking on the behavior of pill bugs. Nail polish, queen-bee marking, and a non-marked control group were used to mark the insects in various ways (Drahokoupilová & Tuf 2012). After marking, exploring, resting, feeding, and hiding behaviors were observed for 24 hours (Drahokoupilová & Tuf 2012). Although there was no difference in the survival of marked individuals, large behavior differences were found (Drahokoupilová & Tuf 2012). Marked individuals displayed hiding behavior for much longer periods of time compared to the control group (Drahokoupilová & Tuf 2012), which provides evidence to support the potential for scents to alter the behavior of pill bugs (Armadillidium vulgare). 

When it comes to the scent of mint, pure peppermint oil has been found to act as a repellent to certain arthropods, such as mosquitos (Koc, Oz, & Cetin 2012). To evaluate the repellant effect of mint on mosquitos, researchers Koc, Oz, and Cetin (2012) utilized hydrodistillation to create essential oil out of the above-ground portion of air-dried mint plants. They placed mosquitos and the mint oil in a glass Y-tube to test the behavior of the mosquitos when exposed to the oils (Koc, Oz, & Cetin 2012). One arm of the Y-tube contained 20 microliters of oil, and the other arm functioned as a control, containing nothing (Koc, Oz, & Cetin 2012). Female mosquitoes were placed in the final branch of the Y-tube, and were left in the device for 30 minutes (Koc, Oz, & Cetin 2012). The insects were observed and their preference for one of the Y-tube arms was recorded (Koc, Oz, & Cetin 2012). The mosquitos showed a high level of aversion to the arm containing the mint oil, indicating that the mint had a strong repellent capability.   

Previous research indicates both that pill bug behavior can be altered by nearby scents, and that mint oil can potentially repel insects. This experiment will combine this previous research to determine the effectiveness of crushed dried peppermint leaves as a natural deterrent to pill bugs. We hypothesize that whole crushed dried peppermint will serve as a natural repellent to arthropods.  We predict that when placed in a choice chamber pill bugs will move away from the peppermint leaves. In our experiment, we predict that placing peppermint oil in a habitat will act as a deterrent, causing pill bugs to avoid the oil.

Materials and Methods

  • Pill Bugs, Armadillidium, Living, Pack 12 (from Carolina supply)
  • One Choice Chamber
  • 8 Quarts EXO-TERRA Plantation Soil Terrarium Substrate 
  • Exo Terra Faunarium, Flat Home 14 inches long x 8 inches wide x 6 inches high
  • 2.2 ounce Tetra TetraFin PLUS Goldfish Flakes with Algae Cleaner Water Formula
  • Driew Plant Mister, Fine Mist Spray Bottle for Cleaning Solution Gardening Trigger Water Empty Sprayer 10oz (Black)
  • 8 ounce Crushed Peppermint Leaves (Mentha piperita)
  • Leaves and Twigs
  • Coronavirus sample

Twelve Armadillidium vulgare will be stored in a faunarium with an inch of plantation soil on the bottom with leaves and twigs to cover the soil surface. This will serve as the crustacean habitat while the bugs are not in the choice chamber. The pill bugs will be fed daily with a spoon full of fish flakes and misted with tap water to keep the habitat moist. The faunarium will be stored in the [Redacted] animal prep room with a cover to keep them dark. The choice chamber will be set up with moist plantation soil in one chamber and  crushed peppermint leaves mixed with moist plantation soil in the other chamber. The pill bugs will be placed in the choice chamber one at a time in the middle of the two chambers to avoid providing bias to the bugs. Each bug will be given two minutes to move towards one side of the choice chamber. The chamber they move to will be considered the preferred habitat. If the bugs do not go towards a side they will be placed back in the housing habitat while the rest of the Armadillidium vulgare are in the choice chambers, then retested at the end with the same protocol. The bugs will test in no particular order, but will be separated after choosing a chamber to ensure no duplicate data. 

Data Collection and Analysis 

The data will be collected by using table 1 to tally how many pill bugs choose each side of the choice chamber. The results will then be analyzed using a T-test to compare the two variables of plantation soil alone or plantation soil with crushed mint. The results will be interpreted using a bar graph to show how many of each outcome occurred.

Plantation Soil
Plantation Soil with Mint
No Choice (Retest)
Behaviors not Listed above

Table 1: Count of possible behaviors occurred

Potential Outcomes

If the pillbugs, all or majority, move towards the plantation only soil this will confirm that mint deters the crustaceans.  In the case that all or most of the bugs move towards the soil with crushed mint, this would conclude that the bugs prefer a habitat with mint scent, oil, or other characters of the mint leaves. The bugs could also be placed in the choice chamber and not move from where they are placed, roll into a ball, or explore the chamber without going to a side. This would give no data to the type of habitat the Armadillidium vulgare prefers in regards to mint.


Cloyd, R., Keith, S., Kalscheur, N., & Kemp, K. (2009). Effect of commercially available plant-derived essential oil products on arthropod pests. Journal of Economic Entomology, 102(4), 1567–1579.

Koc, S., Oz, E., & Cetin, H. (2012). Repellent activities of some labiatae plant essential oils against the saltmarsh mosquito ochlerotatus caspius (Pallas, 1771) (Diptera: Culicidae), Parasitology Research, 110, 2205-2209. 

Drahokoupilová, T., & Tuf, I. (2012). The effect of external marking on the behaviour of the common pill woodlouse Armadillidium vulgare. ZooKeys, 176, 145–154.


Published by Ryan David Tuttle

PhD Graduate student studying Behavioral Neuroscience, Addiction, Stress, Behavioral Economics, and Individual Differences. Former member Ministerial Servant and Pioneer in a Spanish speaking congregation of Jehovah's Witnesses.

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