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Department of Entomology
British Museum (Natural History)
Cromwell Road,
London, SAV.7.
G. A. Webber, Esq.,
Town Hall, March 1st, 194;
Beckenham, Kent.
Dear Sir,
The specimens you sent with your letter of yesterday, an
which were found in a milk-bottle are the empty chrysalid
(known technically as "puparia") of a two-winged fly belong
ing to the Phoridae and known as Paraspiniphora berger
stammi; it has no common name, unfortunately.
The fly has a rather interesting life-history, as it is parasit
in its grub, or maggot stage, on certain snails. At times a
parently the full-fed maggots, instead of pupating within this
shells of the snails, may crawl out and pupate elsewhere; from
the number of cases we have seen, empty milk-bottles, no doub
lying by the sides of hedges, etc., or in gardens, are frequently
chosen. The chrysalids are so securely glued to the sides of the
bottle by the dried milk that when the latter passes through the
washing-machine the jets and detergent fail to dislodge then
The bottles, are, of course, inspected before being passed to the
filler, but here the human element at present comes in, though
it is hoped that after the war a mechanical "spotter" may be
introduced. Anyway, these puparia show up well against the
white milk which also acts as a solvent of the "glue" by whih
the cases adhered to the glass and may float free through the
milk. Such "foreign bodies" are generally spotted by
customer.
Yours faithfully,
(Sgd.) Frederick Lain
It will be noted that no opinion is expressed as to whether the
milk was rendered unfit for human consumption. It so happens
in this case that very little of the milk was consumed, and no
effects were reported by the user.
MILK SAMPLING; SUPERVISION OF DISTRIBUTION.
During the year 87 formal samples of milk were taken in the
course of sale in the district, for chemical analysis. When a sample
of milk contains less than 3% of milk fat, and/or less than 8.5°/ of
milk solids other than milk fat, it is presumed for the purposes of
the Food & Drugs Act, 1938, until the contrary is proved, that the
milk is not genuine, by reason of the abstraction therefrom of mi
fat or milk solids other than milk fat, or the addition thereto of
water. In one case the Public Analyst returned a certificate the
the sample submitted showed the following analysis:—
Milk Fat 2.64%
Solids, not Fat 7.17%
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