Hubbry Logo
MolehillMolehillMain
Open search
Molehill
Community hub
Molehill
logo
8 pages, 0 posts
0 subscribers
Be the first to start a discussion here.
Be the first to start a discussion here.
Molehill
Molehill
Molehill
View on Wikipedia
from Wikipedia
Look up molehill in Wiktionary, the free dictionary.
Several lines of molehills in the pasture.
Trail of mole pass of molehills at Kasori Shell Mound, Chiba city

A molehill (or mole-hill, mole mound) is a conical mound of loose soil raised by small burrowing mammals, including moles, but also similar animals such as mole-rats, and voles. The word is first recorded in the first half of the 15th century.[1] Formerly, the hill was known as a 'wantitump', a word still in dialect use for centuries afterwards.[2]

The phrase "making a mountain out of a molehill" is commonly used metaphorically to mean "to exaggerate a minor problem".

Evidence of burrows

[edit]

Molehills are waste material which come from digging or repairing burrows, and so are usually found where the animal is establishing new burrows, or where existing ones are damaged (for example by the weight of grazing livestock). Where moles burrow beneath the roots of trees or shrubs, the roots support the tunnel, and molehills are less common, and so even a dense population of the animals may be inconspicuous in these places.

Molehills are often the only sign to indicate the presence of the animal and recording their presence may be the most reliable way to determine the number of moles in an area.[3] Commonly they occur in lines along the route of the burrow, but in some cases they may not be directly above the burrow itself but at the ends of short side-tunnels. The mole runs vary in depth from surface runs only a few inches deep, to main runs, some 12 to 18 inches deep.[4]

The disturbance of the soil brings an important benefit by aerating and tilling it, adding to its fertility.[5] Molehills are therefore sometimes used as a source of good soil for use in gardening and are particularly valued by some practitioners of permaculture for fine potting soil.[6] However, they may cause damage to gardens and functional areas of grass such as pasture land, and they represent a minor safety hazard. King William III of England is recorded as dying from complications after he was thrown when his horse stumbled on one.[7]

In locations where mole-hills are not desired, the moles may be killed, or deterrent plants like caper spurge or the related castor bean plant can be planted. The fresh molehills can also be removed carefully as soon as they appear. This leaves the animals and their galleries undamaged and thus reduces the need for the moles to make further molehills when they clear earth out of the tunnels.[8]

Gallery: a mole emerging

[edit]

References

[edit]
Revisions and contributorsEdit on WikipediaRead on Wikipedia

Molehill

View on Grokipedia
from Grokipedia
A molehill is a small, conical mound of loose, fresh raised to the surface by the burrowing activity of various mole worldwide, typically measuring a few inches in height and formed through vertical shafts connected to underground . These structures result from moles excavating as they construct extensive tunnel networks, primarily to hunt for prey such as earthworms, grubs, and , with tunnel depths varying from just below the surface to over 70 cm. Mole activity, and thus molehill formation, peaks in spring during and dispersal periods and in autumn when young moles establish new territories, though established tunnel systems require less frequent maintenance. Moles, such as the (Talpa europaea), are small, mammals measuring 11–16 cm in length and weighing 70–130 g, characterized by short, velvety , tiny eyes, and powerful, spade-like forelimbs adapted for . They spend nearly their entire lives underground, working in bursts of 3–4 hours day and night, and their tunneling behavior not only aids in but also plays a key ecological role by aerating soil, enhancing drainage, and mixing nutrients to improve . In agricultural and settings, moles provide natural by consuming harmful like leatherjackets, cockchafers, and slugs, thereby reducing populations of and crop-damaging without chemical intervention. Additionally, molehills contribute to by creating disturbed patches that favor less shade-tolerant plant species, particularly in productive habitats, influencing community composition along productivity gradients. The term "molehill" also features prominently in the English idiom "to make a mountain out of a molehill," which describes exaggerating a minor issue into a major problem, originating from the contrast between the mole's small earthworks and perceived larger threats. Despite occasional conflicts with humans due to lawn disruptions, moles are recognized as beneficial ecosystem engineers whose activities support and invertebrate population management in natural and managed landscapes.

Definition and Formation

Definition

A molehill is a conical mound of loose, excavated created by subterranean moles of the family as a byproduct of their burrowing activities. These mounds form when moles push surplus upward through vertical tunnels during the construction and maintenance of their underground networks. Molehills can be distinguished from similar soil disturbances, such as ant hills or mounds. Unlike ant hills, which are often structured with organic material, fine particles, and visible entrances or trails, molehills consist of symmetrical, volcano-like piles of pure subsoil lacking vegetation, debris, or organized features. In contrast to mounds, which are typically fan-shaped or crescent-like with plugged tunnels and coarser , molehills are uniformly conical and result from subsurface excavation without surface entry points. The term "molehill" derives from the Old English words "mol" (meaning mole) and "hyll" (meaning hill), first recorded in English around 1450 as a compound word.

Formation Process

Moles excavate primarily using their enlarged forepaws, which act like powerful scoops to loosen and displace earth from underground tunnels. This loosened material is then pushed backward by the mole's body and propelled upward through narrow vertical shafts, often called chimneys, to the surface where it accumulates as a conical mound known as a molehill. The process is a byproduct of the mole's lifestyle, enabling efficient tunnel construction while minimizing surface exposure. Molehill formation typically takes place during the expansion of feeding tunnels or the digging of new systems, as moles seek to access prey or establish territory. This activity is favored in loose, moist soils like sandy loams or peaty grounds, which allow easy penetration and displacement; conversely, dry, compacted, or clay-heavy soils hinder excavation and result in fewer visible mounds. The timing of molehill production aligns with periods of heightened burrowing, peaking in spring (March to May) and fall when soils are workable due to moderate temperatures and moisture, and populations—the moles' primary —surge near the surface. In active areas, this can lead to 90-190 molehills per acre, reflecting intensive digging by resident moles. For the (Talpa europaea), each molehill generally displaces about 3-5 kg of soil, varying with species-specific behaviors and local conditions.

Physical Characteristics

Size and Shape

Molehills exhibit a characteristic morphology as small mounds of loose soil displaced during burrowing activity. For common species such as the eastern mole (Scalopus aquaticus), they typically measure 6-24 inches (15-61 cm) in diameter at the base and 2-8 inches (5-20 cm) in height, though dimensions can extend to less than 12 inches (30 cm) in diameter and 5-8 inches (13-20 cm) in height in more favorable conditions like fertile or moist soils. The shape is generally a symmetrical cone or dome, often volcano-like, with a central crater-like depression indicating the exit shaft from the underlying . The edges are smooth and crumbly, formed by successive loads of pushed upward, sometimes showing on the surface. Size and shape vary by soil type and mole , influencing the mound's stability and appearance. In sandy soils, molehills tend to be smaller and flatter due to less cohesion, while in clay-loam soils, they form taller, more defined structures. Species-specific differences include the (Scalopus aquaticus) producing larger and more dispersed hills compared to the (Condylura cristata), which creates relatively smaller mounds near wet areas. The average volume of soil per molehill is 0.5-1 liter. Characteristics described primarily for North American species; European molehills (Talpa europaea) may differ, with average area ~0.14 .

Soil Composition

Molehill soil originates from subsoil layers typically excavated by moles from depths of 15 to 60 cm (6 to 24 inches), distinguishing it from the organic-rich at the surface. This subsoil is composed mainly of fine particles, including , clay, and , with minimal organic content due to its deeper below the biologically active surface horizon. The lack of results in a material that is initially low in microbial activity and weed seeds, often described as relatively sterile compared to . In terms of nutrient profile, molehill soil frequently exhibits higher concentrations of minerals such as calcium and magnesium, alongside lower levels, than adjacent surface soils; inorganic is also elevated in disturbed molehill areas. The of this is generally higher—neutral to slightly alkaline—contrasting with potentially more acidic top layers in grasslands. These differences arise from the vertical transport of materials during burrowing, exposing subsurface profiles with distinct chemical signatures. The predominantly mineral nature of molehill soil, often exceeding 90% inorganic content, further promotes rapid and if the mounds are not manually flattened, leading to quick integration or dispersal of these materials.

Ecological Role

Soil Aeration and Nutrient Cycling

Mole burrowing and the subsequent formation of molehills play a crucial role in enhancing . By displacing to create tunnels and mounds, moles increase , which facilitates greater penetration of oxygen, water, and plant roots into deeper layers. This improved structure promotes better gas exchange and reduces compaction, contributing to overall . In terms of nutrient cycling, the exposure of subsoil through molehills mixes it with surface layers, redistributing essential minerals such as and incorporating more evenly. This process stimulates microbial activity, which accelerates the of organic materials and enhances nutrient availability for . Studies indicate that mole-disturbed soils exhibit elevated levels of inorganic due to increased mineralization rates from better . Quantitatively, mole activity via molehills can turn over approximately 21 m³ (32 tons of dry soil) of soil per hectare annually, functioning as a form of natural plowing that integrates subsoil properties with the topsoil.

Biodiversity Impacts

Molehills, formed by the burrowing activity of moles, create disturbed soil microhabitats that favor the establishment of pioneer plant species, such as grasses and certain weeds, by providing open, nutrient-enriched patches in otherwise stable grasslands. This disturbance can temporarily inhibit the growth of established vegetation through uprooting and soil displacement, but over time, it promotes greater plant species diversity by facilitating seed germination and colonization in ecosystems like meadows. These mounds also function as key foraging and developmental sites for insects, with the bare ground and warmer microclimate supporting larval stages of species like the grizzled skipper butterfly (Pyrgus malvae), which rely on such disturbances for oviposition and early growth. Molehills influence vertebrate populations as indicators of mole presence, supporting predators that hunt moles and other subterranean prey.

Relation to Moles

Burrowing Behavior

Moles exhibit a solitary , aggressively defending individual territories. Burrowing behaviors and territory sizes vary by and ; for example, in North American such as the (Scalopus aquaticus), territories can span up to 2.5 acres (1 ha) for males and slightly less for females. These territories consist of complex systems, with minimal overlap between individuals except during brief mating periods. Moles burrow extensively within their territories, constructing 100 to 300 feet of new tunnels daily, depending on conditions and activity levels; the resulting molehills often signal ongoing expansion of these underground networks. The primary driver of this burrowing behavior is for invertebrates, including earthworms, grubs, and other that constitute the bulk of a mole's diet. As moles excavate deeper tunnels in pursuit of prey, they push excess upward through vertical shafts, forming distinctive surface mounds known as molehills. This process is most evident during hunts that extend below the shallow feeding layers, where displaced material accumulates visibly on the surface. Burrowing activity intensifies during moist seasons, such as spring and fall, when softened facilitates easier digging and earthworm populations rise closer to the surface. In temperate zones, males show particularly elevated tunneling during the breeding period from to March, constructing additional tunnels and mounds while seeking mates across expanded ranges. Their tunnels commonly reach depths of up to 3 feet, providing access to stable subsurface environments for hunting and shelter.

Types of Burrows

Mole burrows associated with molehills can be classified into three primary types based on their depth, function, and surface manifestations: surface runways, deep tunnels, and nest chambers. These structures reflect the moles' , nesting, and navigational needs within their subterranean habitats. Surface runways are shallow feeding tunnels, typically 2-6 inches deep, constructed just below the grass layer to allow moles to hunt for invertebrates like earthworms. These tunnels often appear as linear ridges or subtle furrows on the surface rather than distinct, piled molehills, as the displaced soil is minimal and spreads along the path. Deep tunnels serve as permanent burrows for nesting, , and long-term residence, extending 12-40 inches below the surface with straighter paths and reinforced stability from compacted . Vertical shafts from these tunnels emerge at the surface, ejecting to form prominent, volcano-shaped molehills that mark entry or exit points. These deeper systems provide protection from predators and environmental fluctuations. Nest chambers form the core of the burrow system, consisting of central, spherical rooms approximately 4-6 inches in , intricately lined with dry such as grass and leaves for insulation and comfort. These chambers are often surrounded by multiple exit shafts that radiate outward, resulting in clustered mounds of excavated at the surface, which help ventilate the space and facilitate quick escapes. In the Townsend's mole (Scapanus townsendii), burrow systems may include specialized "fortress" structures centered around the nest, characterized by a single large exceeding 76 cm in and up to 45 cm high, which indicates the presence of an extensive, protective .

Human Interactions

Agricultural and Impacts

Molehills significantly impact by creating raised mounds and ridges that disrupt mowing and result in uneven surfaces, often leading to scalped areas where lawn mowers remove too much grass. The displaced subsoil, which is typically nutrient-poor and compacted, smothers existing turf, causing grass to dry out and die, while the overall aesthetic degradation affects residential yards, parks, and courses. These mounds introduce bare patches that require additional maintenance to restore smooth, healthy coverage. In agricultural contexts, molehills contaminate harvested such as hay and with particles, which can comprise a notable portion of the material and hinder proper curing, thereby diminishing feed quality and nutritional value for . Tunneling activity further interferes with root crops by dislodging from the , disrupting plant stability, and reducing overall field productivity in vegetable and cultivations. These effects are particularly problematic in pastures and cropped fields where mole activity covers and promotes uneven growth. Despite these drawbacks, molehills offer some benefits in managed landscapes like orchards, where the upturned acts as a form of natural fertilization by mixing deeper into the upper layers, enhancing and potentially supporting improved health and fruit production through better exposure. This bioturbation process aids in incorporating , though such positives are often outweighed by damage in .

Control Methods

Trapping represents one of the most effective methods for controlling moles and reducing molehill formation, targeting the animals directly in their active tunnels. Scissor-jaw traps, such as the Out O' Sight model, and harpoon traps, like the Victor brand, are commonly used by closing off a section of the tunnel and inserting the trap at fresh molehills or raised ridges to capture the mole as it attempts to repair the disturbance. mole trappers report success rates of 75-90% when traps are placed correctly in active tunnels during periods of high mole activity, such as spring or fall. To maximize efficacy, users should first identify active burrows by flattening ridges and monitoring for repairs within 24 hours, ensuring traps are set in moist, loamy soils where moles are most prevalent. Repellents offer a non-lethal alternative for deterring moles from treated areas, though their effects are generally temporary and require reapplication. Castor oil-based granules, such as those in products like Mole Max or Victor Mole & Repellent, work by coating earthworms and soil particles, causing digestive upset in moles and encouraging them to relocate; these are applied by spreading over the lawn and watering in, providing protection for 4-6 weeks before needing reapplication. Ultrasonic devices emit high-frequency sound waves through stakes inserted into the ground, aiming to irritate moles and disrupt their foraging; while some users note initial reductions in activity, effectiveness often diminishes after 1-3 months due to , making them suitable as a supplementary rather than primary method. Both types are humane and but perform best when combined with other strategies, as standalone use may only displace moles to untreated areas. Habitat modification focuses on altering the environment to make it less attractive to moles by targeting their primary sources and preferred conditions. Introducing beneficial nematodes, such as Heterorhabditis bacteriophora, can reduce populations of grubs and other insects that moles consume, indirectly limiting their availability and encouraging departure from the site; these microscopic worms are applied via drench in late summer or early fall for optimal results. Improving drainage through and avoiding overwatering hardens the , making burrowing more difficult and reducing earthworm abundance, a staple of the mole diet; for instance, incorporating like enhances while decreasing moisture retention. These changes promote long-term prevention without chemicals, though they may take several months to show noticeable impacts on mole activity. Integrated pest management (IPM) for moles integrates multiple approaches, including monitoring, barriers, and targeted interventions, to achieve sustainable control while minimizing environmental harm. Regular monitoring of fresh molehills allows for timely action, while installing physical barriers like hardware cloth or wire mesh buried 24-30 inches deep around gardens or lawns prevents extension; gravel-filled trenches can similarly deter digging by creating unstable substrate. Combining these with or repellents in an IPM framework reduces recurrence by promoting ecosystem balance and limiting reliance on any single method. Legal s for moles vary by country. For example, in , moles are protected under national law (§44 Federal Nature Conservation Law), requiring permission for control measures. In the UK, moles have no specific protection beyond general anti-cruelty laws.

References

  1. https://www.montwt.co.uk/wildlife-advice/molehills
  2. https://ryanlawn.com/blog/what-seasons-are-moles-most-active/
  3. https://wdfw.wa.gov/species-habitats/living/species-facts/moles
  4. https://extension.psu.edu/moles
  5. https://www.sciencedirect.com/science/article/abs/pii/S1146609X10001013
  6. https://www.thefreedictionary.com/molehill
  7. https://www.seattle.gov/documents/Departments/SPU/EnvironmentConservation/IPM/MolesIPMFactSheet.pdf
  8. https://extension.missouri.edu/publications/g9440
  9. https://animaldiversity.org/accounts/Talpidae/
  10. https://dictionary.cambridge.org/dictionary/english/molehill
  11. https://redinational.com/how-do-i-differentiate-between-mole-hills-and-ant-hills/
  12. https://www.aaipest.com/pest-control-blog/whats-the-difference-between-a-gopher-and-a-mole/
  13. https://www.oed.com/dictionary/molehill_n
  14. https://onlinelibrary.wiley.com/doi/full/10.1002/esp.6008
  15. https://pmc.ncbi.nlm.nih.gov/articles/PMC4929419/
  16. https://extension.entm.purdue.edu/publications/ADM-10.pdf
  17. https://www.in.gov/dnr/fish-and-wildlife/wildlife-resources/living-with-wildlife/eastern-mole/
  18. https://www.maine.gov/dacf/php/gotpests/othercritters/factsheets/moles-ark.pdf
  19. https://www.havahart.com/mole-facts
  20. https://besjournals.onlinelibrary.wiley.com/doi/10.1046/j.1365-2664.1999.00411.x
  21. https://njaes.rutgers.edu/fs025/
  22. https://www.researchgate.net/publication/237269502_Contribution_of_molehill_disturbances_to_grassland_community_composition_along_a_productivity_gradient
  23. https://www.researchgate.net/publication/229513143_Soil_nutrient_fluxes_and_vegetation_changes_on_molehills
  24. https://www.sciencedirect.com/science/article/abs/pii/S0265931X17308226
  25. https://www.sciencedirect.com/science/article/abs/pii/S1146609X15000351
  26. http://www.eje.cz/artkey/eje-201304-0013_molehills_as_important_larval_habitats_for_the_grizzled_skipper_pyrgus_malvae_lepidoptera_hesperiidae_in_c.php
  27. https://www.purdue.edu/fnr/extension/spring-season-is-mole-season/
  28. https://trapyourmoles.com/mole-info/
  29. https://www.cjonline.com/story/lifestyle/home-garden/2015/04/10/home-living-fighting-pesky-mole/16632698007/
  30. https://www.nwf.org/Educational-Resources/Wildlife-Guide/Mammals/Moles
  31. https://extension.missouri.edu/news/wet-weather-triggers-mole-activity
  32. https://ipm.cahnr.uconn.edu/management-of-moles/
  33. https://tomcatbrand.com/en-us/product-types-tips/learn-about-moles.html
  34. https://njaes.rutgers.edu/FS025/
  35. https://www.pubs.ext.vt.edu/420/420-201/420-201.html
  36. https://icwdm.org/species/other-mammals/moles/mole-biology/
  37. https://got-moles.com/how-deep-do-moles-dig/
  38. https://edis.ifas.ufl.edu/publication/UW080
  39. https://www.mammal.org.uk/british-mammals/mole
  40. https://www2.gov.bc.ca/assets/gov/environment/plants-animals-and-ecosystems/species-ecosystems-at-risk/brochures/townsends_mole.pdf
  41. https://yardandgarden.extension.iastate.edu/encyclopedia/moles-lawn-control
  42. https://ipm.missouri.edu/meg/2012/3/how-to-control-moles-and-reduce-turfgrass-damage/
  43. https://blogs.cornell.edu/nysipm/2020/10/14/dealing-with-mole-problems-in-turfgrass/
  44. https://smallfarms.oregonstate.edu/sites/agscid7/files/ec987.pdf
  45. https://naturalresources.extension.iastate.edu/encyclopedia/moles-damage-management
  46. https://extension.psu.edu/moles/
  47. https://redinational.com/what-is-the-success-rate-of-professional-mole-trapping/
  48. https://extensionpubs.unl.edu/publication/g1538/na/html/view
  49. https://www.victorpest.com/victor-mole-and-gopher-repellent-yard-spray-1bottle-m8002-all-questions
  50. https://redinational.com/do-ultrasonic-mole-repellers-really-work/
  51. https://pestmgt.com/blog/how-to-get-rid-of-moles-in-your-yard/
  52. https://redinational.com/how-can-i-make-my-yard-less-attractive-to-moles/
  53. https://extension.illinois.edu/blogs/good-growing/2022-04-21-what-do-when-your-mole-hills-have-turned-mountains
  54. https://ipm.ucanr.edu/home-and-landscape/moles/
  55. https://trapyourmoles.com/installing-barriers-to-block-mole-entry/
  56. https://redinational.com/what-is-integrated-pest-management-for-moles/
  57. https://home.army.mil/bavaria/application/files/1015/3926/0990/Environmental_Moles.pdf
  58. https://www.rspca.org.uk/documents/1494935/9042554/Living%2Bwith%2B-%2Bmoles%2B-%2Bformatted%2B%2528V1.2%2529%2B-%2B2017.pdf/61a0a5f6-b28e-c46e-042d-5b8fecf54207?t=1553171460360
Add your contribution
Related Hubs
User Avatar
No comments yet.