Issue
18
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3
We moved into 35 Bartlemy Road in December 1977. Built in the 1930’s as part of a new estate on what were open fields, it is a three bedroom semi detached house with a fairly large garden, 30 metres by 12 metres, a detached garage and two sheds. A greenhouse was added in 1990.
The first slug I remember seeing in the garden was black, fairly small with an orange sole. I had been interested in slugs and snails from childhood, but at the time I was not a member of the Society and remember being frustrated at not being able to identify such a distinctive species from my only reference book The Young Specialist Looks at Molluscs. I now know that they were Arion hortenis agg, but they appeared to be totally black with no grey colouring or lateral bands as described in the book. Since then a few specimens have been dissected at various workshops and the population appears to be Arion distinctus. This species is still in the garden, but I think it is by no means as common as it once was. It is the slug most commonly brought into the house stuck in the cats’ fur.
When we moved in there was very little vegetable garden, but as soon as we extended it and started planting I became aware of Deroceras reticulatum, particularly as a pest taking young lettuces as soon as they were planted. They remain a pest, but overshadowed by another species mentioned later. Deroceras panormitanum also occurs in small numbers and is usually found under bricks or in rubble.
Two other slugs which I frequently found, particularly in autumn, were Tandonia budapestensis and Tandonia sowerbyi. Originally I did not particularly view these species as being pests as they were most often found in the vicinity of the house. This view rapidly changed once I started growing a few potatoes. Tiny holes in the potatoes often revealed a large cavity inside and sometimes the culprit, usually T.budapestenis. A neighbour recommended the potato variety ‘Kestrel’ which I understand has a thicker skin making it less prone to slug attack. This has proved to be good advice and it is a variety which has given me good yields and certainly suffered less damage.
In the early days I was very excited to find one specimen of Limax maximus at the back of the shed. This was a species which I could identify with certainty. There was a scheme running at the time requesting records for the species, but they wanted the actual specimen sent to them. I sent in the record, but wasn’t prepared to part with the actual slug. This species seems to be more common now and is found in the greenhouse and behind the sheds and garage. It is a species I am always pleased to find.
I was also excited to find one specimen of Boettgerilla pallens behind the garage in a pile of bricks. This find was made around 1985, but I did not find another specimen until 2007, when I found one in the front garden while replacing some garden edging. It was a least 20cm below ground, under a brick supporting the edging.
Not mentioned so far is Arion rufus. I am certain this was not present when we moved in. I have often blamed myself for introducing it in leaf litter or soil samples, but it is present on our local allotments only 100 metres away and I am assured that it has ‘always’ been there, so perhaps I am not guilty of introducing it. Irrespective of how it got into the garden, it is now by far the most common and damaging pest species. We have counted nearly 200 in the garden in one night (see page 114 of the Conchologists’ Newsletter, No. 147, December 1998). I have tried many ways of protecting my young plants and now resort to using slug pellets containing metaldehyde. I do not sow lettuces or runner beans directly into the ground, but start them in pots. When planting out the young plants I place one or two pellets close to plants and find that the slugs are attracted to these so that they are killed or paralysed before damaging the plant. I hope that by minimising the number of pellets used, and by burying any dead slugs as soon as possible I will not be harming other wildlife.
Lehmannia valentiana appeared in the greenhouse in small numbers 10 years ago. I suspect that it was introduced with garden centre plants. Over recent years the numbers have increased considerably and the species is now found both in the greenhouse and around the garage and occasionally in the house. I had not thought of it as being a particular pest, but being curious about damage to my greenhouse cucumbers I mounted video surveillance with an infrared security camera for a few nights. Three Lehmannia valentiana appeared at about 11 pm., grazed on the cucumbers for about 20 minutes and moved off. At midnight a single Arion rufus appeared and did considerably more damage in just a few minutes before moving on. Armed with the timings I was able to remove the culprits and prevent further damage. I avoid using slug pellets in the greenhouse, because Limax maximus is attracted to them (see page 267 of the Conchologists’ Newsletter, No. 161, December 1999).
The latest slug to arrive has been Limacus flavus. The first one I found was curled around the top of a milk bottle left on the doorstep by the milkman in the early hours of the morning. The species is now found in fairly large number around the front of the house. We have found them indoors in the conservatory and in the kitchen. The trails left for us suggest that we are receiving more that occasional visits.
Arion rufus is a colourful interesting slug and not one I would wish to be without, but I sometimes wish there were rather less of them. Otherwise I enjoy sharing my garden with the various species of slugs and I am happy to accept some loss of garden produce for the interest they provide.