184 
Psyche 
[August 
Bremus fervidus belongs to the Dumoucheli group and to the 
Pocket-makers, and it therefore is among the representatives of 
these groups that we should look first for species which are given 
to honey daubing. 
As already mentioned, Bremus colonies are occasionally 
infested by parasitic bumblebees of the genus Psithyrus. Ac- 
cording to Hoffer (1888, p. 132), this sometimes occurs in almost 
every second colony of certain species. Other Bremus species, 
on the other hand, never harbor these parasites (Cf. Sladen, 
1912, p. 257), and this, as the writer pointed out recently (1922), 
also seems to be the case with Bremus fervidus. It can hardly be 
doubted that the honey daubing habit of Bremus fervidus plays 
an important role in keeping Psithyrus from breeding in its 
nests. 
In his “Catalogue of British Hvmenoptera” Smith (1855, 
p. 210) makes the following statement in regard to the apparent 
immunity of certain English Bremus species from Psithyrus 
infestation: “Although I have taken or examined a very large 
number of the nests of Bombus [Bremus], I have only oc- 
casionally met with the parasites [Psithyrus] in them; but 
never in the nests of the brown bumble-bees.” All of these 
brown species to which Smith refers ( agrorum , distmguendus, 
helferanus, and muscorum ), like Bremus fervidus, are Pocket- 
makers. Plowever, Hoffer (1888, p. 132) .found that in Austria 
two of these brown species ( agrorum and helferanus ) are fre- 
quently victimized by Psithyrus campestris Panzer, and Wagner 
(1907, p. 78) reports that in Russia Bremus muscorum suffers 
severely from the depredations of various species of Psithyrus. 
Bremus distivguendus Morawitz, the other species mentioned by 
Smith, is very similar to Bremus fervidus in structure, 5 
coloration, and habit. It is also very closely related to Bremus 
latreillellus Kirby 6 so that Morawitz (1881, p. 238) and Friese and 
Wagner (1910, p. 75) merely look upon it as a variety of the 
latter. According to Sladen (1912, p. 257), Bremus latreillellus 
is not preyed upon by any species of Psithyrus; nor has any 
5 Cf. Sladen (1912, p. 187) and Franklin (1912-13, I, p. 392). 
6Cf. Hoffer (1882-83, II, p. 72); Radowszkowski (1884, p. 77); Sladen (1912, pp. 184, 187); 
d Lutz (1916, p. 503). 
