Slugs In Garden: Pests Or Perhaps Not?


Slugs In Garden

Slugs are often the most damaging of all the garden pests to a wide variety of garden plants, particularly in the seedling stage.

As many as 200 slugs can live in a square meter of the garden, and as well as attacking the foliage, most of these slugs also devour the roots of many plants.

Slugs like damp conditions and so are much more common in wet years and areas of the humid garden, particularly from March to October.Slugs In Garden

They are favored by loam and clay soils that retain water and oils with a high humus content but are less common on highly organic peaty soils.

Slugs tend to hide away under rank vegetation, wood, or stones during the day to emerge at night to feed, providing the conditions are sufficiently warm and humid.

They make irregular holes in the leaves, flowers, and stems, with the minute teeth covering their rasping tongue.

This feeding soon results in making the plant very unsightly. Several slug species are common in gardens.

Slug Types

The three critical types in Britain are the field slug, Deroceras reticulatum, and some related species; round-backed slugs such as the garden slug, Arion hortensis; and keeled slugs, Milax species, which tend to attack plant roots.

All of these need mild damp conditions in which to breed, and so they avoid dry areas. Gardens generally provide slugs with both an appropriate microclimate and plenty of living plants and dead organic matter on which to feed.

During frosty or dry weather, slugs bury themselves deep in the soil and hibernate over winter.

Slugs Lifecycle

Most slugs have similar life cycles. Several hundred eggs are laid annually in batches of ten to 50, most commonly during spring or sometimes autumn by a hermaphrodite parent; these are the result of cross-fertilization by another hermaphrodite in the autumn or winter.

Most of the translucent eggs are laid during the spring, usually in damp soil or rotting plant debris well away from cold and dry air.

The eggs can hatch fairly quickly into miniature replicas of the adults, but often this process is delayed until the weather improves.

As a result, in some species, such as the garden and keeled slugs, the complete cycle can take two years, but the slug takes a year in the field.

The rather variably colored, brown to cream, Deroceras reticulatum is probably the most destructive of the surface-dwelling slugs that predominantly attacks foliage but can also damage seeds and vegetative planting material.

It can reach nearly 4cm long. Although the black slug, Arion ater, is very much larger (14cm) and more obvious than the garden slug, Arion hortensis, which is also black. Relatively harmless.

Slugs Control

Slugs are difficult to control, and attempts at eradication are rarely, if ever, successful in heavily infested gardens.

Although slug poisons can be sprayed, for many years, the most popular method of control has been to scatter pellets of a bran bait poisoned with metaldehyde or methiocarb.

However, their effectiveness is reduced if the pellets become wet during rain, so often, the bait is kept sheltered underneath a piece of tile, slate, or broken flowerpot.

Other baits include beer or milk, which are poured into traps that drown the slugs.

Other traditional baits include baiting with half orange skins or pieces of other vegetable material or even sacking, which are inspected regularly, and any slugs present are destroyed.

More recently, a nematode parasite of slugs, Phasmarhabditis hermaphrodita, has been discovered.

This is being developed into an effective and environmentally safe method of biological control.

It has been tested to make sure that it does not affect earthworms and other animals and plants.

It does attack beneficial water snails, so the area around ponds should be avoided. Although it works best during the warmer summer months, as it is killed at 35°e, it cannot survive in

birds and other warm-blooded animals. The nematodes enter the saddlelike mantle on the back of the slug, where they release bacteria.

These bacteria quickly multiply and provide food for the nematodes, which multiply, causing the mantle to swell due to by-products produced during feeding.

This injury stops the slugs from feeding, and they burrow into the soil to die after becoming completely invaded by the nematodes.

The soil becomes contaminated with the larvae of the nematode, thus escalating the effect of biological control. It has been tested to make sure that it does not affect earthworms and other animals and plants.

A couple of products formulated in clay mud are available in Britain by mail order for drenches in open soil or containers.

The contents of the sachet that arrives within ten days should be stirred into the water then further diluted and applied via a coarse-rose watering can.

The soil that is to be treated should be moistened before treatment and kept damp but friable afterward.

Take care to clear away plant debris and mulches that could limit soil penetration by the nematodes.

It is best to treat a week before sowing or planting to allow the nematodes time to find and infect the slugs.

What Is the Best Solution

Slugs aren’t all that bad, really, yet they always seem to be top of the ‘most hated pest’ list every year.

The truth is there are only a tiny handful of the UK’s 40 or so slug species that eat us out of house and home (or garden), while the rest go about their business as handy garden composters, harmlessly dispatching dead plants and animals.

I know, it doesn’t seem that way when you pop outside excitedly to check on your new hostas to find, well, no hostas. But they don’t eat everything in sight, and only a few cause any real problems.

In my garden, they’re probably about 90 percent intriguing wildlife-watching opportunity and 10 percent pest.

These terrestrial mollusks sport many different shapes, colors, sizes, and habits, though we tend to lump them all into one ‘pest’ category.

It’s usually those small ones that have snack plants, while larger ones can be
spotted helping you out in the compost heap.

Check What Slug Type You have in Your Garden.

Take a look and see what sort you’ve got: the nicely mottled green cellar slug eats algae, compost, and mold (whatever floats your boat!) while the cream-striped, brown-grey Sowerby’s slug devours any fresh seedling or leafy lettuce you’ve got on the menu.

Did you know they possess thousands of teeth and can live for six years?

The stuff of nightmares, perhaps, but also quite charming. Almost like garden pets. Well, maybe not!

Here’s a thought: slugs aren’t to blame for their plant-eating antics. It’s us who are creating problems for ourselves.

The vast majority of plants they don’t eat, yet we persist in providing them with their favorite, fast-growing tasty morsels and then getting annoyed when eating them.

We build slug havens with veg patches, fertile ground, and lush leaves – it’s no wonder they go mad in some gardens.

Of course, those with dry, sandy plots may wonder what the fuss is all about; they only like warmish damp spots and heavy soils.

I suppose if you have a slug problem, you might relax a little, accept them and work with what you’ve got. And don’t grow hostas and salads!

Keep weeds down, grow (among others) unpalatable bergenias, foxgloves, geraniums, euphorbias, and encourage hedgehogs, birds, ground beetles, and frogs who love to eat them.

A few nibbles here and there won’t do any harm.

Of course, if it’s gone beyond a few nibbles, the best controls are organic slug pellets and nematodes.

The latter you mix into your watering can – harmless to anything else but slugs.

But my advice is to leave them be large. Upset the garden’s natural balance, and it can do a lot more harm than the slugs ever will.


Comments are closed.