Of Mice and Parasites

OF MICE AND PARASITES by

GRACE

GRIFFITH

It all began at a meeting of the Botanical Section of the Suffolk Naturalists' Society in January, 1956.

Lord Cranbrook leaned across and asked if I had any mice in my wood, and if so would I collect and identify them and note their distribution. I Said I had not been interested in mice previously and I knew little about them but if I could help in any little way I would be glad to do so.

I got four Longworth traps and placed them in my wood following Instructions given by Lord Cranbrook. I chose what I thought was a suitable site on the edge of the wood, put comfortable mouse bedding in the inner Chamber and a varied bait of com, nuts and apple in the run. For four months I watched the traps. When I was away I had the help of a village boy who kept an eye on them for me. DĂźring the whole time none of the traps caught anything. On July 7th, I took the traps up and put them in the wood shed thinking that I had omitted some essential preparation or that the shortage of rabbits from myxomatosis had led to a wholesale disappearance of mice.

Within an hour of putting the traps in the shed the door of one was closed. I could not attend to it then, but having been assured that the trap would make a good home for a few hours and knowing that there was food in it I left it until the evening.

When I came to remove the mouse I found it had died. It was a large mouse with the characteristic pectoral cross of yellow fĂźr on its ehest and I feit sure it was a speeimen of Apodemtis flavicollis, but not having seen one before I thought I would send it to Lord Cranbrook for verification and with this in mind I eviscerated it. I found in the abdominal cavity a tape worm about three inches long and thinking it might be of interest I sent it along with the mouse carcase.

Lord Cranbrook was good enough to take the tape worm to the Natural History Section of the British Museum for identification and found it was Catenataenia lobata (Baer) and was the first to be recorded in Britain as being found in Apodemus flavicollis.

He also brought back a request for any more parasites whether internal or external since little work had been done in this field and there was much yet to be discovered about the two varieties of wood mice, Apodemus sylvaticus and Apodemus flavicollis (Wiltoni). In addition they would welcome speeimens of parasites from any of the small mammals. Dr. Theresa Clay was most anxious to get sucking lice from these animals and she showed

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me some that she had and how to collect and identify them.

My interest was thus aroused and I began to examine all the mice that I caught.

By the help of typed Instructions and printed leaflets, I was able to collectfleasand lice from all the mice I caught. Those that were dead I opened and searched for internal parasites as well, but I found no other tape worm. Friends also sent me dead mice so that I soon had quite a laboratory going for mouse parasites.

Each mouse as caught, whether alive or dead, was popped into a cotton bag, (the live ones were transferred by a wcll-gloved hand) and a string was tied round the open end of the bag. I then brushed over the outside of the bags holding the live ones with a cotton wool swab slightly damped with chloroform. This quietened the wee beastie and enabled me to open the bag and take it out. I then swabbed its fĂźr with the cotton wool and collected all that feil off on a sheet of white paper. The chloroform quietened the fleas as well as the mouse and in this way I was able to go through the fĂźr with a pair of forceps and a small comb and the sleepy inhabitants dropped gently on to the white paper which was then folded and the contents tipped into a small glass jar containing 70% alcohol.

Each type of mouse examined had its own jar to keep the finds separate and when these were dated and labelled I set them aside until I was able to take them to the Museum where I was always welcomed and thanked for what I brought along.

I enjoyed the fun of taking to that vast building a few fleas and lice in small glass tubes !

Within a few days of my visit I had letters recording the names and sex of the specimens with thanks from various entomological departments and requests for more specimens not only from the mice themselves but also from their nests. I received fĂźll instructions how to follow mice to their nests by painting their feet with radio-active isotopes and then tracing their route when released by a geiger counter. I have had no opportunity to do this yet but it certainly sounds exciting.

Of the parasites sent along two were noted as being the first record of these fleas found on Apodemusflavicollisin Britain : 1 male Nosopsyllus fasciatus (Bosc). and 1 female.

1 female Hystrichopsylla talpae talpae.

Later in the year the Director of the Museum acknowledged the gift of thesefleasin a very elegant certificate.