Monday, March 1, 2010

The Epic Battle

It is time. Arm yourselves and prepare to defend your property. An invasion is imminent; even now the advance scouts can be seen. You must be ruthless; this is no time for namby-pamby bleeding hearts!

Okay, so our invaders are mollusks and most are pretty tiny. But slugs are the number one complaint we hear from home gardeners. And no wonder, because they are hard to control and their damage can deface a garden overnight. If we faithfully defend our plants now, we will at least stem the tide.  The best course of action, in my opinion, is multi-level.

First, I recommend baiting with an iron phosphate product. The reason I prefer this is because the other widely available active ingredient in slug bait, Metaldehyde, is classified by the U.S. Environmental Protection Agency as a 'slightly' toxic compound that may be fatal to dogs or other pets if eaten.  The severity is related to size of the animal, so birds are at high risk. Check out this website for more specifics on the danger.

Iron phosphate, on the other hand, is a substance that is sometimes included in fertilizers. You can find the EPA report online. The active ingredient is coated with “bait”-such as wheat gluten-that is highly attractive to slugs. Cereal-based baits attract and kill more slugs than non-cereal-based baits, such as liquid slug baits.  It is most effective spread just before plants are breaking ground in the spring, when the “salad bar” is sparse. Apply bait after rain showers, as slugs like to come out and feed then.

At the Miller Garden in Seattle, iron phosphate is applied once in the spring and once in the fall. Autumn is a good time to bait, because you can kill the reprobates before they lay eggs. As the rains return in the fall and mornings are damp, the slugs will come out of their underground hiding places. Since 90% of the slugs are underground at any one time, even with best practices you can’t kill them all, but you can make a big dent. It seems that, in my yard, the bait becomes less effective when it is always available. So, the twice a year protocol works best for me.

Secondly, go after individual perpetrators. Handpicking is a time honored method to do this, preferably after dark with a flashlight and a bucket of soapy water to finish them off. I’m not a fan. Instead, I fill a spray bottle with 1/3 ammonia and 2/3 water and go on slug safari in the cool of early summer mornings. It is worth is to pay the extra money for a sturdy bottle; I can hit a 4” slug at 20 paces.

Remember, every slug you dispatch had the potential to produce about 40,000 offspring. And yes, I mean EVERY slug because they are hermaphrodite-having both male and female organs-so every individual can lay eggs.  There are three stages in the life cycle: eggs, immature stage and adults. They can overwinter in any stage, mature in less than one year and may live two or more years-unless you intervene.

My last weapon is my least favorite, but I sometimes resort to it in desperation. The keg party is a nearly fool-proof method for snagging those slimy topes. Use a small plastic container, such as a 6 oz drinking glass, yogurt or margarine tub. Half bury in the soil and fill with the cheapest beer you can find. They apparently are not connoisseurs, unlike Washington state bears.   You will need to empty it within a few days-the longer you wait, the nastier it will be. But with this method you will even catch the little bitty guys that you’ll never find when you are shooting from the hip.

It is also worth the time to eliminate slug hostels from your yard. Slugs love dark, moist areas and you will find them congregating under boards, stones, debris, ground covers and the like. This can work to your advantage if you regularly cleaclip_image001r out these dens of iniquity by handpicking (good luck with that.)  We have built a fabulous slug condo made of stone-ah in our garden-an unintended result of our retaining walls. I can’t dismantle it get to the buggers, but I can bait nearby and check the walls regularly with my trusty ammonia launcher in hand.

Here’s a solution I haven’t tried yet: recently, USDA scientists have shown that caffeine is an effective slug deterrent. Caffeine is not currently registered as a pesticide in the U.S., so there are no caffeine-based slug control products available. However, so many people use coffee grounds as nutrient-rich mulch around garden plants that many Starbucks bag up their grounds and offer them to interested customers.  I’m going try this one around my Ligularia, which is completely irresistible to and pretty indefensible from slugs. If it works, it will be a breakthrough for me!


  1. Thanks for the tips, Susan. I will look for the cereal-based slug bait for sure. I appreciate your knowledge!

  2. Not only was it educational it was very entertaining! Thanks for your valuable assistance