Fall Slug Control
Mary Bardens, Lowell, IN
   Did you know that fall is still egg-laying time for slugs? We tend to forget about them as the hosta leaves change color and head into dormancy. The slugs will be active until the soil temperatures reach freezing, when they will go into hibernation until the spring thaw. So, until that happens, they will lay eggs. Mating will occur from August until mid-October with eggs laid about 30-40 days after that. Look for 1/8 to ľ inch sized gelatinous clusters of about 20-30 spheres. Older slugs will lay larger quantities. The eggs may be hard to see as they can reflect their surroundings. When the eggs are near hatching, the spheres may become cloudy. Slugs love those piles of leaves, damp from heavy dews and fall rains. Look for them under anything that will keep them cool and moist. Other favorite places will be flowerpots, boards, cooled compost piles, at the edge of large rocks or under mulch.
So the big question is-what to do?

Slug eggs in winter

Slug eating hosta petiole

 1 Eliminate their favorite spots. Clean up the old hosta leaves and other debris. Turn the compost pile to make it too hot to be attractive for them. Check under those flowerpots before you store them.
 2 Set a slug trap. They are attracted to any fermenting food: beer or a mixture of sugar, yeast and water. Sink a tuna can with the rim 1Ē above ground level so they will crawl in and drown. If you put it flush to the ground you run the risk of drowning ground beetles, which are a slug predator. Colorado State U. Entomology Professor Whitney determined that their favorite types of beer were Kingsbury Malt, Michelob & Budweiser. Empty often. Replace beer weekly. Commercial slug baiting stations are available. If you leave a flat board on the damp ground, you can scrape them off in the morning.
 3 Go on a slug hunt. Late at night or very early in the morning, grab a flashlight and bucket of soapy water to drop them into after hand picking. Slugs are nocturnal and love to hit the all night hosta diner. Watch for the little ones. Like teenagers, they are voracious eaters. You can even use a handheld vacuum to suck up the little pests, but you may want to warn the next person to use it.
 4 Encourage a predator to hang out in your garden. Toads, turtles, owls, Mourning Doves, and Robins love slugs. There are also some predators that we may not be too thrilled encountering in the hosta bed that also feast on slugs: black ground beetles, opossums, shrews, wild turkeys, chipmunks, skunks, moles and Northern Ringneck snakes.
 5 Iron Phosphate baits - Slug bait pellets made from this can stop slugs without poisoning birds, small pets, humans or earthworms. Though they are not sure exactly why, iron phosphate inhibits the slugs from feeding, and it is actually good for the soil. It is sold under the names of Sluggo, Es-car-go, and Saferís Slug & Snail Bait.*
 6 Metaldehyde baits - This is a molluscicide, which means it is a poison that kills slugs, and can also be purchased in a form to spray on the hostas. It is very effective for killing slugs, but also kills earthworms and other things with which it comes in contact.  Great care in handling, application and storage must be observed.**
 7 Ammonia Solution - A solution of household ammonia (1 part ammonia: 5 parts water) in a spray bottle with the nozzle set on a direct stream and sprayed directly on the slug will kill it in a few seconds. This solution will not harm the plants.
 8 Barriers - Copper tape placed around the hostas as a barrier repels slugs because as they slime across it, it causes a toxic reaction like an electrical shock. However,  if they find a leaf lying over the barrier, they can get in. A product called Slug de-Fence is composed of a low density polyethylene plastic and vacuum grade table salt. It repels the slugs unless they try to get over it, and then the salt gets them, but it may also look like you tried to wrap your plants with little trash bag fences.
 9 Abrasive Materials - Eggshells, coffee grounds, sand, cedar shaving, hair or ash are abrasive materials which may be placed around plants which will scratch the slugs' bodies causing them to dehydrate. Diatomaceous earth can also be used, but it is a very fine powder and you must wear a mask to keep from inhaling it. These products must all be kept dry to work, and they must be reapplied after a rain.
10 Biological Controls - In Europe you may purchase the parasitic nematode Phasmarhabditis hermaphrodita, which is naturally occurring in their soil. This is a microscopic worm that enters the slugís body through natural openings and releases bacteria that multiplies and kills the slug in 4-16 days. It does not bother earthworms. It also has the ability to recycle and become part of the ecosystem in the absence of a host, which would make it good for long term management. It is marketed under the name Nemaslug, but donít try to add it to your Thompson & Morgan order just yet; itís still illegal here. Agricultural scientists collaborating from Ohio State U. and Purdue U. are doing parasitic nematode research to help protect crops in no-till fields that are most susceptible to slug damage. They are also evaluating the American parasitic nematode cousin, but so far none is as effective at the European relative. They are compiling data showing the safety of importing nematode Phasmarhabditis hermaphrodita into our soil.
Editors' Note: In the time since this article was written, new information about the iron phosphate slug baits has become available. 

*The iron phosphate products contain the chemical EDTA which is not listed on the label, and which makes them neither safe nor organic. We recommend if you use these products to exercise the same care you would with any poison. These products have been shown to harm earthworms.

**Studies have shown that the metaldehyde baits do not harm earthworms.

New Author Bio - Mary moved to Lowell, Indiana in 1988 when she married her husband, Neal. Her in-laws gave her her first hostas plants, although they called them funkia. Later she and Neal happened on Dogwood Farm Nursery and were hooked. They now have over 700 varieties. 
   She is currently a member of the NW Indiana Hosta Society, the Indianapolis Hosta Society, the Great Lakes Region Hosta Society, and the American Hosta Society. When NWIHS was new, she held a number of positions, but now serves only as newsletter editor. In 2009 she accepted the position of Newsletter Editor Coordinator for the AHS, assisting the local hosta clubs across the United States in exchanging news, ideas, and articles.
   She attended her first AHS Convention in Cleveland (2005) followed by Indianapolis and St. Louis. Hosta College in Piqua, Ohio, is an annual treat each March when nothing is green in NW Indiana. Her favorite hosta in her collection is 'Simply Sharon' and she is continually amazed at the variations that appear each year as the new hostas are introduced.

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