How I learned to value slugs and snails
Researches and Discoveries in the Garden
and snails must be among the most visible, and certainly the most infuriating
of pests for the organic gardener. The demoralisation of seeing the telltale
slimy trail, and the remains of a lettuce or runner bean crop, is a common experience.
I love the idea of growing my own food, but until two years ago it never exactly
came to reality. And the reason for the failure was largely because of the slimy
little blighters. I gave up even trying with supposedly simple crops like spinach
or lettuce. I unwillingly shared my potato crop with the garden molluscs. My
tomatoes and runner beans had major fortifications around them (moats, stilts,
copper tripwires, sawn-off plastic bottles and bits of plastic drainpipe as
collars around the plants) until they were robust enough to survive unassisted.
It was a continual battle. I squashed the tiny slugs or snails I found around
the plants I wanted to keep, and threw the larger ones in the compost bin, on
the basis that they might usefully chomp something there.
However, I had a nagging suspicion that the remedies I was using were dealing
with symptoms and not causes. What is it that prompts slugs and snails to do
so much damage? Last year I inadvertently stumbled on a possible explanation.
For reasons unconnected with molluscs, I started using copper garden tools
in the garden in spring 2001. By August I noticed that the potato crop on a
small raised bed was doing well, and put it down to the quality of the manure
and the fact that I had earthed them up with grass clippings. There were so
many potatoes that they were pushing through the surface, so I started picking
them off, trying to avoid disturbing the roots. Then, ever optimistic, I sowed
some lettuce seeds in the greenhouse. A week later they had started to sprout,
and late one night I did a prowl with the torch. I found two large slugs in
the area, picked them up and deposited them in the compost bin. Ten days later
the lettuces were still there, such a surprising event that I didn’t know
what to make of it. In the absence of any other course of action, I promptly
forgot about it. At the end of August I harvested my potatoes, and by this point
I realised that something decidedly strange was going on. Even having had several
meals from the potatoes I had already picked, there were still 36 pounds of
potatoes on that raised bed. And of the entire crop, only six potatoes had slug
miracle continued in 2002. May was warmer and wetter than average in the UK,
and not surprisingly, high levels of slugs and snails were reported by many
gardeners. In my garden, admittedly, most of the Cosmos disappeared from the
flower garden, but I had a bumper spinach crop in the spring. The runner beans
survived (minus four) without any fortifications at all. I saw slime trails
in the greenhouse, but the tomatoes were completely untouched by molluscs. In
June 2002, I passed a personal milestone. I do not throw the snails out of the
greenhouse any more.
What is going on? A possible clue lies in the fact that molluscs’ blood
contains haemocyanin, based on copper, whereas human blood is based on iron,
haemoglobin. I wondered, what effect does this have on a slug’s behaviour?
Perhaps it is thanks to the existence of haemoglobin in our blood that humans
are able to think at all. The circulation of the iron in our blood around the
body is the anchor of an independent electromagnetic field. Iron can be magnetised,
so one piece of iron can hold a different field from another. This property
of the iron in our blood allows us to think different thoughts and feel different
feelings from the person standing next to us. Even though we live within the
Earth’s magnetic field, we have the ability to maintain our own independent
field within it.
It would be a very different scenario if our blood were based on haemocyanin.
Copper is non-magnetic and highly conductive, so we would have no independent
field. Instead, we would be intensely aware of external electromagnetic variations.
We would be sensitive to differences in the Earth’s magnetic field in
a way that is beyond our imagining, and we would be compelled to respond. We
would not be capable of any independent action at all.
Maybe this is what governs the behaviour of slugs and snails. They aren’t
attracted by my newly-transplanted lettuce seedlings, but are compelled to respond
to the disturbance that has gone on in the soil there. The disturbance may be
the residual magnetism from a rusty nail, or the magnetic signature from the
iron tool which turned the soil. This is what attracts them. When they arrive
in the area, they need some sustenance, so they eat my seedlings. If I throw
these slugs in the compost bin, the disturbance still exists in the lettuce
patch, so they or other slugs and snails will still be attracted to it.
working the soil with copper tools has the opposite effect. As copper is conductive,
it leaves no magnetic residue, but rather it connects up any breaks in the magnetic
field. So there is less to attract the slugs and snails. They wander over the
area, but don’t stop for long, and so don’t need to eat anything.
This may give a hint to the role of the garden molluscs. If my thinking is
correct, then the slugs and snails play a valuable part in the ecology of the
garden. They represent the highly conductive metal, copper, roaming around the
garden, rather like those robot lawnmowers that are supposed to keep the lawn
trimmed. They help the land to link up with itself, by smoothing out any disruptions
in the flow of the geomagnetic field. The slime trail is their visiting card.
So in my garden, I now leave them to do their job.
I am not academically trained in any of the areas touched by these speculations,
and would appreciate any comments or feedback from those who are. I can’t
explain the survival value of this behaviour to the slugs and snails, for example.
It is also undeniable that they do seem to target certain plants, which is another
area worth investigating. They must be responding to extremely small variations
in the geomagnetic field, but that also seems plausible. After all, Homeopathy
also works with scientifically insignificant quantities. In the meantime, I
am delighted that the slugs and snails do not devastate my garden any more.