D. Kbilin 107 
Helicosporidium in a specimen of Mycetobia pallipes, invading the peripheral 
portion of its fat-body. 
2. Hericia hericia (Robin) Kramer (1899) (Acarina, Tyroglyphidae). 
In addition to the above-mentioned Dipterous larvae, the exudate which 
fills the wounds of the elm tree contains also a very interesting mite belonging 
to the family Tyroglyphidae. This mite, Hericia hericia (Robin) Kramer, 1899, 
is undoubtedly the most frequent inhabitant of the exudate. It was discovered 
and very well described by Robin (1868) who found it in the exudate of elm 
trees in France. 
The mite has been since found in England by Michael (1903, Vol. n. 
“Tyroglyphidae,” pp. 31-38, Pis. XXIII-XXIV) who gives in his monograph 
of British Tyroglyphidae a complete description of all its stages. Concerning 
its habitat he writes: “This species usually lives in a semi-aquatic condition, 
wading in the sap which exudes from splits in the bark of elm trees, or under 
loose bark of these trees, and in the brown saccharine matter which collects 
there. In such situation it is often present in great numbers; it is also found, 
Text fig. 5. A leg of Hericia hericia heavily infested with Helicosporidium showing the spores and 
filaments 
but less frequently, in similar situations on the oak. I have not found it on 
other trees, but it is quite possible that it may exist on them.” 
I myself found this mite abundantly, often covering the entire surface of 
the wound. 
On many occasions I have carefully examined large numbers of this mite 
without finding a single parasitised specimen, but recently (October, 1920), 
whilst collecting the Dasyhelea larvae, I noticed a portion of the body of 
Hericia with two legs attached to it, the whole filled with filaments and a few 
complete spores of Helicosporidium. I believed at first that I was dealing 
with an empty skin of a dead Hericia which was invaded by a small Dasyhelea 
larva parasitised and killed by Helicosporidium , but on careful examination of 
other mites, I soon discovered eight entire specimens, three of which were 
alive, all showing Helicosporidium in different phases of its life-cycle. 
Text-fig. 5 shows a leg of a very heavily infested specimen of Hericia , the 
whole body of which is invaded with the spores and a large number of filaments. 
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