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Jeff Lowenfels: Slugs and the arachnids that eat them

  • Author: Jeff Lowenfels
  • Updated: September 28, 2016
  • Published August 7, 2014

All of a sudden, the slugs start to appear and so do the questions about them. It never fails that along with the first few questions or comments about slugs, gardeners start to question what is up with all the daddy longlegs (aka harvestmen) that seem to also appear from nowhere.

Let's start with the slugs. What gardener has not encountered these shell-less gastropods, which are essentially land mollusks (think clams and such). As noted in "Teaming With Microbes," these critters are actually an important part of the soil food web: For every one you see above ground eating your lettuce or kale, there are five or so underground, using the same rasp-like teeth to grind up dead material, thus making it more accessible to fungi and bacteria.

Ah, but no matter. The one that you do see is all that you care about. Slugs cut holes and rasp down leaves. They love the cole crops that do so well here. Slugs travel great distances at night and can follow each other's slime trails to a great food source. They travel, by the way, by creating this slime and skating along it. There would be a good business in renting out slug-eating ducks hereabouts. Short of fowl, there are all sorts of baits to attract and kill slugs (and snails). Beer or yeast and sugar water in shallow containers will attract slugs and snails. There are also lots of commercial traps. Those that are made of iron phosphate are the safe ones when it comes to children and pets. The others contain metaldehyde, which is not safe. Don't use them. If you can find loose iron phosphate, it can be sprinkled on lawns and gardens.

Of course, hand-picking works, too, but you have to get at it early and keep at it. Try watering in the afternoon and coming out in the evening when the slugs are active. Slugs are slimy and hand-picking can be messy. A pair of latex gloves might be in order. In any case, make sure you wash your hands, lest you pick up some of the parasites in the slime that carry meningitis.

Which brings me to harvestmen, or daddy longlegs, more properly opiliones. These long-legged animals are called harvestmen because they appear in numbers around harvest. The smaller-bodied ones are males, which also have longer legs. The females lay eggs in the fall.

If you pick up a daddy longlegs, you may notice the odor they give off to protect themselves from birds and other predators. Do be careful handling these guys; a leg may fall off. This happens as a protective mechanism. The best way to observe them is in a terrarium.

Opiliones are not spiders, though they are arachnids. They have one-part bodies, not two, and they lack web-making ability. They are not poisonous and they don't even have fangs, as do spiders. Instead, they have mouth-parts like a king crab. They grab their prey and hold onto it while they eat it.

Which brings me back to slugs. One of the things that opiliones eat are slugs. Really. So one of the reasons you are seeing more opiliones in your yard is that there are more slugs. They also eat aphids, mites, the occasional spider or bird dropping and dead insects. Don't complain, unless you don't have any.

Jeff’s weekend garden calendar for the week of August 8

Potatoes: Keep hilling. They are not ready until after they flower and are sweeter if harvested after a frost. You have weeks to go.

Raspberries: Pick. Freeze. Eat. Give away through PAR. Do not waste food.

Sweet peas: Pick flowers so new ones will keep coming.

Lawnmower: Consider sharpening or replacing your blade(s).

Cauliflower: Only produces once, unlike broccoli which will continue to send off new flowers.

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