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remains limited to the jar in question, especially if the vaseline 
ring is thickened from time to time. 
But restricting the extention of the infection is but an indirect 
measure against the evil, which may sometimes assume large 
dimensions, when its appearance must also be accounted for by the 
bad quality of the meal or the bran used. The experiences in this 
matter were at the outset so disappointing as to almost discourage 
any further investigations. So it stands to reason that with great 
satisfaction the experience was made that all at once everything 
changed for the better from the moment when the cultures were 
transferred into incubators with a temperature of + 25° Celsius. 
It sometimes occurred, it is true, that here and there the mite 
appeared (especially in humid weather), but by a general application 
of the vaseline ring, a sooner sieving and renewal of the food and 
an occasional raising of the temperature to 28°, the situation could 
be kept under control, so much so that Tyroglyphus farinae was 
no longer a formidable enemy. 
5. The Gathering of Pupae and Beetles. 
When the pupae make their appearance, they should be removed. 
Even if one does not wish to sort them into males and females, one 
has better not wait (for various reasons) until the beetles emerge. 
When the layer of bran is not too thick the pupae work them- 
selves up to the surface, either wholly, or partially, so that only 
the distal end of the abdomen sticks out above the bran layer. The 
sidelong broadened lateral edges of the segments 5 to 11 incl. 
(Fig. III) are provided with 3 or 4 sharp stings and wonderfully 
adapted to render this working up possible easily and quickly. 
That these broadened lateral edges with their stings are only 
serviceable in the pupae stage is apparent from the fact that this 
edge with the stings is cast off together with the pupal skin and 
does not return in the beetle. At a temperature in the incubator of 
25° ©, the larvae jars may, after the last gathering of pupae, stand 
7 days, before they require to be inspected on pupae again. At the 
temperature mentioned the development from pupa to beetle takes 
about 9—12 days. 
The pupae collected were put in deep saucers of a diameter of 
abt. 138 ¢.m., the bottom of which was covered with a patch of 
black sateen. As soon as the beetles emerge they crawl, shunning 
the light, under the patch or the curled-up borders of it. The number 
of cast moults that remain on the sateen, denotes the number of 
beetles that keep in the shade somewhere. 
— a i. 
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