Homeschool Garden Club - Slugs and Snails
Its official slugs are the gardener’s number one enemy. Did you know that about 95% of the slug population is below ground, which means there are up to 200 slugs in every cubic metre of soil. slugs produce two forms of slimy mucus - a thick sticky form that covers bodies to prevent them drying out, and a thinner mucus that they use to travel over the ground with. Most slug species have two pairs of tentacles on their head, which can be retracted in to their body and regrown if lost. the longer pair are used to see and the shorter ones are used to find food. Just behind the slug's head is a saddle like feature called the mantle. on onside of this is a hole called the pneumostome, through which the slug breaths. The rest of the body is made up of the foot and tail, which produces rhythmic muscle flows that propel the slug forwards on the bed of thin mucus. Slugs are hermaphrodites meaning they are both male and female. These slimy molluscs lay up to 100 - 150 eggs per year, in batches of 10 to 30. these opaque white round eggs are suss ally found under stones and longs, or just beneath the service of the soil. Juvenile slugs hatch with 4 to 12 weeks and mature 12 to 15 weeks later and can live up to 18 months but many perish in harsh winters. However, the most interesting fact is that the slug’s blood is actually green.
Snails are gastropods that grow a shell that they can retract into, while slugs have no shell or just a small internal one. Without a shell slugs can rapidly dehydrate and die. They are usually associated with wet, damp environments and feed mainly at night. During the day (particularly hot summer days) slugs will rest in moist, shady areas.
The Grey Field slug is a surface feeder and the one mostly found in around the veg plot. I find these in the grass around the washing line. There have been occasions when nipping out at night to bring in the washing I have stepped on these with my bear feet in the low light. there is something ultimately disgusting about a squished slug between your toes and their slim can be a little bit irritating.
The Black Garden slug is also a surface feeder but it can also burrow deep and feed on root crops such as potatoes, swede, turnip and beetroot.
Keeled slugs are olive green, dark grey or black in colour and easily recognised by the pale orange keel that runs down their back. They can grow up to about 7cm long and spend most of their life underground eating the roots of vegetables.
There is one other thug of a slug to watch out for and that is the Spanish Slug. As its names suggests it has come in from outside the UK. It has evolved under much harsher conditions and has had to survive with in a hotter and drier climate than here, where fresh lush new growth is sparse. It has now spread to Northern Europe, where it has found itself in an environment that provides it with plenty of food and where it can remain active for a greater part of the year. It can lay many more eggs than our native slugs and is starting to out compete our local home grown slugs.
The campaign to purge my garden of slugs and snails this spring was going alright or so I thought until I found some more hardy slugs inside my water butts again and two intrepid snails climbing up my front door in broad day light. It has been a strange spring this year with all weathers unpredictably been thrown at us. However, it has been surprisingly dry. My water butts are almost empty which is unusual for this time in April. Now that the soil has warmed up and seedling are going out in to the ground I am on the hunt for the pests to make sure that my vegetables are mine and not dinner for the wild life.
There are two parts to my plan. The first is to deny them places to hide – hence the regular checking the water butt rims, keeping the vegetable garden tidy and weeding regularly between the crops. The weeds help the slugs and snails to both hide and feed.
The second part of this is to reduce the numbers. If they are climbing the front door in full sun there are too many in the garden! I have used nematodes again this spring to eat all those eggs but I need to catch that 5% of the adults on the surface eating my seedlings.
A tired and tested method to trap slugs and small snails is to place half a grapefruit among the rows of vegetables. Eat the grapefruit first and then place the shell upside down like mini domes. Any molluscs in the vegetable patch will shelter under the grapefruit as the sun rises, they also enjoy pith so tend to stick around. Check the grapefruit peel regularly and feed directly to the chickens.
Another method is to trap the slimy beasties, you can use beer traps. As a non-drinker, I don’t have access to beer. But if you do - you will need to check with the beer drinker in the family that you have permission to use one of their beers. Cheap beer is fine to use. Use a recycled plastic bottle with the thinner top bit cut off so you have the stubby bottom bit of the bottle. Bury it up to its waist near the vegetables This protects the ground beetles who can’t climb in. Pour a little bit of the beer in to the bottom. The slugs should make a direct trail for the beer and thanks to their sticky mom-foot can get in to the beer but then can’t get back out. Alternatively you can buy purpose built traps. What you do with them next has never been made clear to me. Feeding them to the chicken would be ok but I am guessing not too many in one go as we don’t want drunk chicken.
In the meantime, I am out looking for them at the end of the evening, I am sowing back up veg, trying to entice a local hedgehog to visit by keeping my hedgehog holes in the fence clear.