The International Slugfest -- How Big Is Your Slug?

The International Slugfest: A contest to locate and photograph the largest slug in the world.

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Fig. 1. Philomycus carolinianus. (Bosc, 1802) Carolina Mantleslug. The above slug measures 56.42 mm from tip of its foot to its head. It was photographed at 7:00 PM on 14 Feb. 2005 crawling on a cypress tree. The temperature was around 68 degrees F. This variety of slug occurs throughout the southeastern USA, west to Texas and north to Maine and Ontario. It is active during the evenings and can often be seen after rainy days when it comes out to feed upon lichen and algae growing upon bark or other surfaces. PHOTO COPYRIGHT 2005 BY TAL

The International Slug Festival is seeking the largest slug in the world!

The International Slug Festival is a contest to find and photograph the largest slug in the world.

To enter this contest you must photograph a slug in its natural environment and obtain an accurate measure of the slug's length. No means may be used to artificially extend your slug entry.

Slugs should NOT be collected or held in captivity and fed to try to make them larger. This is a competition to photograph slugs in nature and in no way should any slug be hurt, harmed, molested or disturbed in the process of observing and photographing it.

Measuring Slugs

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Fig. 2. Philomycus carolinianus (Bosc, 1802). Carolina Mantleslug. This slug measured in at 80 mm. It was observed at 23:45 hrs. on 12 Feb. 2005 feeding upon algae and lichen growing upon a dead live oak tree. Also bracket fungi was abundant upon this live oak tree. The temperature was measured at 55 degrees F. Visual measurements were taken of the slug's length. Note that one must be careful to position the ruler and camera so as to avoid too much parallax. Of course with a slug it may expand and contract, twist and turn, so getting an accurate measure of its length often requires waiting until it extends itself to its full length. I'd love to see how large other slugs are around the country and the world so please get your Limax photos coming in! Thanks! PHOTO COPYRIGHT 2005 BY TAL.

How to measures slugs. You may measure your slug by photographing it against a metric ruler. You may use a photograph to verify the measure of the slug by accurately recording the distance between two points upon a photograph where the slug was observed crawling. In Fig. 1 above, the slug was calculated to be 56.42 mm long after making an accurate measure of two points upon trunk where the bark was chipped off. Visual measures were also taken and in Fig. 2 both visual measures were taken and a photographic record of the slug's length was made against a ruler when the slug was fully extended moving down the tree (orientation of photograph was varied to make reading the ruler easier). The official measure is taken from the head to the tail end of the slug's foot; sorry the slug's eye stalks (optical tentacles) are not included in its length. Finding a slug with the longest eye stalks may a different contest for the future. Please try not to disturb your slug when photographing it.

How To Make Your Entry

Beginning October 1, 2008 any photographs selected for usage may be reprinted on promotional gifts and apparel to help raise funds.  So please ONLY send photographs which include a completed entry form.  This will be a way you can also get your nice designs upon high quality merchandise.  Also you will be eligible to receive an annual prize which may show your photograph on a product.  You current photos is not available unless you submit the complete entry form.

After photographing your slug against a metric ruler, send a digital photograph of your slug to Slugfest. Please indicate the location (city/state/province), date and time where the photographs was taken and the name of the photographer. You may also indicate the scientific name of the slug should you know this. You should also specify how long your slug was measured to be which should be verifiable by observing the photograph.

All entries become the property of The International Slugfest and may be reprinted or published on this site or elsewhere to promote The International Slugfest. No entries can be returned. Credit will be given to the photographer as PHOTO BY JOHN DOE.

There is no limit to the number of entries you may make. The contest has a perpetual duration and is open to anyone, anywhere in the world. Postings will be made of entries and the longest slug to date will be featured. This contest does not discriminate against people or slugs based upon race, religion, color, sex or national origin. Our philosophy is that every slug is a good slug; some are just longer than others!

No pics of human slugs or organs are allowed in this competition so please keep your privates to yourself! Sorry, but this had to be said for certainly someone would otherwise send in pics that would have to be disqualified for their utter tastelessness.

Slug Stuff

Please help promote and support The International Slugfest. A variety of "Slug Stuff" is provided for your enjoyment!

Please click on pic to visit store and purchase these items

Please click on pic to visit store and purchase these items.

Please click on pic to visit store and purchase these items

Please click on pic to visit store and purchase these items.

Please click on pic to visit store and purchase these items

Please click on pic to visit store and purchase these items.

Please click on pic to visit store and purchase these items

Please click on pic to visit store and purchase these items.

Save The Slug

The usage of organic insecticides and highly toxic and poisonous chemicals to kill slugs and insects also kills many of harmless animals and may cause cancer in humans. Please help save the slug and humanity. Everyone is encouraged to practice organic gardening and to buy foods which are grown organically. By helping to save the slug and gardening organically you will reduce the carcinogens in the environment and save the lives of people, pets and other animals!

Please click on pic to visit store and purchase these items

Please click on pic to visit store and purchase these items.
Available in pink, tan, skyblue, and exotic jade.

Other Slug Photographs

There are many interesting aspects about slugs which may be captured using photography. Perhaps when you go slug hunting you will not find the longest slug, but you may stumble upon some very pretty slugs -- or the most ugliest slug. Or perhaps you will get some photographs of a slug orgy. Or some colorful slugs. And yes, should you find a slug with really long eye stalks, this would be interesting to see and share with others. Please send in these type of slug pictures also. They will be used to produce a slug gallery. Thanks sluggers!


Please visit these links. Don't forget to go slug hunting. Make a night of it and see who can find and photograph the largest slug.

Slugs via Yahoo

Snails & Slugs

Slugs via the EnchantedLearning.Com This site has a very good diagram of a slug's body parts.

Virtual Guide to UK Molluska (Snails and Slugs)

Featured Creatures: Slugs via IFAS, University of Florida This site has an excellent key to Florida slugs including exotic species found in many other states.

The Recent Gastropoda of Oklahoma, Part VIII. The Slug Families Limacidae, Arionidae, Veronicellidae, and Philomycidae This report by Branley A. Branson of Eastern Kentucky University has a very nice description of the various slug families with illustrations. It requires Acrobat Reader to view.


You may support The International Slugfest with a donations of any amount which will be considered a gift to a private individual and is NOT tax deductible. You may also make donations via to the email address of Thank you for your consideration and support.

You may also help by purchasing design items featured on The International Slugfest or available via our sponsor. Thank you for your support.

How about 'em slugs!

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Fig. 3 Kissing slugs? Look again. This is actually one large slug curled about itself! It was photographed along the Hoh River Trail in Hoh Rain Forest, Olympia National Park, July 5, 2008. Nikon Coolpix P3 Camera set on auto. Copyright 2008 by Michelle Hill, Seattle, WA.

Do you have any great slug pics? I'd really like to see more photographs of slugs engaged in all sorts of behavior: feeding, mating, feeding, mating, feeding, mating ... or whatever else slugs do. :-) Please keep your slug pics coming! Thanks!

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Fig. 4. Banana slug observed July 3, 2005 at 7:15 PM PDST, estimated at 169 mm. Canon 10D, with a 50 mm macro lens. Photo © 2005 by Mark Bonnington.

Mark Bonnington of Redmond, Washington, entered the photograph Shown in Fig. 4 of a banana slug (probably Ariolimax dolichophollus) measuring approximately 169 mm.

This entry sparked a reply regarding banana slugs and the need to try to avoid parallax when photographing slugs; i.e., to try to photograph the slug and ruler in the same plane parallel to the lens of the camera to avoid distortion. Obviously if the ruler is in the foreground it will give the illusion that the slug is longer than if the slug and ruler are both perpendicular to the camera lens.

These comments may be helpful to others in photographing their slippery when wet friends:

Dear Mark:

Thank you very much for your entry in the International Slug Festival. I would like to encourage you to endeavor to get additional photographs of these wonderful and beautiful slugs that come into your back yard. Please try to get some more pictures. This is a challenge. Please try to get your best possible photograph of the largest slug fully extended. Try to measure the length of the slug when fully extended accurately. This can take patients and some skill as disturbing the slug causes them to curl up or shy away.

When photographing slugs also try to avoid parallax. This means there should be no angle to the slug and lens especially when taking the photo with the ruler next to the slug. The camera should be perpendicular to the ruler. You can experiment to see how accurately you can get a measure of length from this method. Example, photograph two rulers positioned exactly as was your slug. Then you can see how much parallax effects the true measure of the ruler in the background as made by the ruler in the foreground. This experiment will actually enable you to more accurately estimate the measure of a slug or other object when there is parallax. Do you understand what I'm saying here?

From your picture the slug, ruler and camera are at about a 45 degree angle. The camera needs to be perpendicular to the slug and ruler or such that the lens is in a plane parallel to the slug and ruler to reduce parallax. Of course all cameras and lenses introduce distortion. A 50 mm lens gives less distortion. But if you experiment with two rulers placed in a field of view, you can see how changing the angle introduces depth of field and how parallax results in a distortion of measure such that the ruler in the fore ground does not give an accurate measure of the slug or object in the background. The object and the ruler have to be in the same parallel field to get an accurate measure of length.

If you look at how my slug photo was done you will see that I endeavored to get the slug and the ruler in the same plane. I actually held the ruler in one hand and quickly took the photograph with the camera in the other hand, taking a sequence of photos rapidly, then picking out the best photo later. Also I measured the slug as best I could when it was fully extended so I would know what its length was to be sure I recorded this accurately from the photograph.

You are very fortunate to live where they have these large yellow banana slugs (Ariolimax sp.). Actually I'd be very interested in seeing more photographs of them. Can you try to get more pictures. I'd also like to see photographs of them eating, say upon a mushroom, lichen or other vegetation. And it would be great to get a photo of these slugs mating if you could manage that.

Please at least try to get some more pictures of the longest one of these monstrous slugs. They are at least twice the size of the slugs I've observed in my area.

Oh, also, please when you put a copyright on the photos, please use smaller lettering and put this in the corner. I will be sure to give you full credit and copyright for your photos so this should not bother you. I am going to add the photo you sent to the slug fest page and may include this email to help others. Also, please do a bit of research and see if your can identify the species of the slug you are photographing and send that with your future entries. I have also seen many photographs of banana slugs myself. I recall they have even appeared in National Geographic before. However, the person who takes the photos should submit the species name of the slug. I will then check to be sure you entered the correct name. There are links at:

Note at the later site that the "littlest" and "Largest" slugs at Big Basin are just estimated in size and that no great effort was made to accurately photograph and record the measure these slugs against a ruler.

Note this article states:

"As we watch three bright yellow banana slugs slime across the walls of a lettuce-filled fishbowl sitting on her coffee table, Harper explains that A. columbianus is sometimes spotted brown like an overripe banana, whereas A. dolichophallus is bright yellow and has a long male organ, as the name suggests."

This suggest your slug may be A. dolichophallus given it has no brown spots.

Note: Banana slugs can grow to be 25 cm or 9.8 inches in length so certainly it would be a challenge for you to get a photograph of one that is at least this long or even longer!

Thanks again for your entry and please do endeavor to get some additional photos. I'd love to see that 25+ cm. slug photo! Surely there is one out there and you are in an area where it may be!

You can make as many entries as you want. Good luck slug hunting! Maybe you can also challenge others in your area to find and photograph that elusive giant banana slug!

Best regards,

Terry Lynch

Featured entries

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Fig. 5 Without a doubt, this is the largest slug photo entry to date (July 2007). This giant was photographed slipping along a basement wall in Rolla, Missouri, in late June, 2007. The slug measures approximately 17.5 cm when fully extended! Photo (c) 2007 by A. S. Lisle. Good job Angela! Looks like you guys are going to have to do some real slug hunting to beat this one!

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Fig. 6 This large garden slug, Limax maximus Linnaeus, was collected by a group of aspiring naturalists, Katie, Maggie, Emily and Mary of Cary, North Carolina. The slug was collected, cared for, photographed and measured with the four aspiring naturalist reporting that it was a whopping 130 mm long when fully extended! However the slug did not cooperated when being photographed and was recorded to be about 117 mm. on the evening of Sept. 22, 2005. Photo © 2005 by Lorraine Mehltretter.

Watch slug's foot as it crawls on glass!

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Fig. 7 As a special featured video you are invited to watch Fredrik Haljesgard's Sala Slug Video Limax maximus Linnaeus, in Motion. The Zip file size 585,248 bytes requires PKUNZIP or compatible utility to unzip and can be viewed with Windows Media Player. This slug was collected and photographed by Fredrik Haljesgard of Sala, Sweden, in a moist, forested area during the fall of 2005 and permitted to crawl over a piece of glass to record its motion using the video feature of a Canon PowerShot G6 camera. The Sala slug measures over 12 cm and is 1 - 2 cm thick, depending upon the degree of extension. If you have never seen a slug or snail move, this is an excellent video which clearly captures the rhythmic pulsation of its muscular foot, moving in waves from the posterior to the anterior of the slug as it slowly moves forward. Photo and video Copyright © 2006 by Fredrik Haljesgard.

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