Many people believe that placing hedge balls, the fruit of the Osage orange tree, around their homes can deter spiders. This article explores the scientific basis behind this popular claim.
What Are Hedge Balls?
Hedge balls are the large, bumpy, yellow-green fruits of the Maclura pomifera tree, also called the Osage orange, native to parts of the southwestern United States (Arkansas, Oklahoma, and Texas).
Historically, the thorny Osage orange trees were widely planted by settlers to create impenetrable natural fences before the invention of barbed wire. Their dense wood was also prized by Native American tribes, like the Osage, for making bows and tools due to its strength.
While hedge balls possess a mild, citrus-like fragrance, they are inedible to humans and contain a milky, sticky sap that can cause skin irritation. The fruit contains various chemical compounds, including triterpenoids, limonene, osajin, pomiferin, elemol, and sesquiterpenoids.
The Science Behind Spider Repellency
Despite persistent belief, scientific evidence does not support that whole hedge balls effectively repel spiders. Spiders frequently inhabit Osage orange trees and even construct webs directly on the fallen fruit, indicating no natural aversion to their presence. Spiders generally do not possess a strong ability to detect airborne odors, which is necessary for a volatile repellent to work.
Research, including studies by Iowa State University, has investigated the chemical compounds found in hedge balls. These studies found that highly concentrated extracts of certain compounds, such as elemol or sesquiterpenoids, could repel some insects like German cockroaches, mosquitoes, and houseflies in very small, enclosed laboratory settings. However, the natural concentrations of these compounds within an intact hedge ball are far too low to produce any repellent effect. In larger, open household environments, any minuscule amount of repellent chemical that might be released would quickly dissipate, rendering the whole fruit ineffective. The Environmental Protection Agency (EPA) has required online vendors to remove claims about the pesticidal properties of Maclura pomifera due to a lack of supporting evidence.
Why the Misconception Endures
The belief that hedge balls repel spiders largely stems from anecdotal evidence and traditional folk remedies. A reason for this misconception is the coincidental timing of when hedge balls become available. These fruits ripen and fall from trees in the autumn months. This period also corresponds with a natural decrease in indoor spider activity, as colder outdoor temperatures lead to drier indoor environments less hospitable to many spider species. People might mistakenly attribute this natural decline to the hedge balls they have placed, perceiving a correlation where none exists.
The power of suggestion and a desire for a simple, natural solution contribute to the myth’s longevity. Some theories suggest the myth originated from a 1950 newspaper article that vaguely claimed concentrated extracts could repel cockroaches, which then evolved into the broader, unsupported belief about spiders. The Osage orange tree is known for having few insect pests, which might have led to the assumption that its fruit possesses repellent qualities. The milky latex exuded by the fruit, a natural plant defense mechanism, could reinforce the idea that it deters pests.