104 
Meg. curvicrus Thoms. cuts pieces of leaves of Plantago. 
Meg. willughbiella Kirby builds partly in the earth and partly 
in disused burrows of Podalirius in clay walls. The cells are formed 
of beech leaves. 
Meg. circumcincta K. builds in sand pits and formes its cells 
of birch leaves. 
Meg. centuncularis L. cuts pieces of leaves of Betula, Syringa, 
Castanea, Fraxinus, Lonicera. 
M. argentata F. is found in sandy places near the coast. The 
nests in sandhills. The cells are formed of pieces of leaves of 
Betula, Syringa, Salix, Cytisus, Robinia, Ulmus, Vitis. 
Å common parasite is Coelioxys mandibularis Nyl, who kills 
the larva of its host and lives on the food intended for this. It 
spinns aåa Cocoon, when fully grown. This however is not the case 
either with C. rufescens Lep. who lives'as a parasite on ColZetes 
daviesana Sm. or with C. vectis Curtis, who occurs with Podalirius 
parietinus L. 
This proves that the parasites of the genus Coelioxys follow 
their hosts in the matter of making cocoons. 
There are two groups of these bees who make special recep- 
tacles for the food for their larva, one in which these receptacles 
are of so substantial and wet-resisting quality that a cocoon (the 
main object of which is to keep out the moisture) is unnescessary 
and therefore has become obsolete both in case of the host and the 
parasites. (Podalirius, Colletes, Prosopis). The second group, on 
the contrary, formes the receptacles out of vegetable matter, which, 
as soon as their object, to keep the honey from flowing out, is ful- 
filled, decay and offer no protection against the moisture. In this 
case a cocoon is necessary and has therefore been retained, both 
by hosts and parasite (Megachile, Anthidium, Osmia). 
