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BULLETIN OF WISCONSIN NATURAL HISTORY SOCIETY. VOL. 3, NO. 4. 
September 8. which furnishes support to the enormous 
mandibles, and at the same time protects 
the head from an attack. 
September 9. The body of the dead host-larva has not 
been entirely eaten by the parasite. 
September 12. The Ccelioxys-larva has moulted. In its 
new form it has a white head with small 
mandibles (Fig-. 6), and resembles some- 
what the larva of the leaf-cutter bee. The 
large sickle-shaped mandibles, and the 
brown flattened head-shield have been en- 
tirely cast aside. 
September 16. The parasitic larva has gradually lost its 
former slender form, and looks much like 
a host-larva. The dry remains of the. leaf- 
cutter larva are still in the nest. 
September 18. Parasite dead. 
2. Ccelioxys rufitarsis, 8m'. f a parasite of Mega chile melano- 
phcea, Sm., and Megachile latimanus, Sag. 
Megachile melanopluea constructs its cells in the ground, 
mostly not more than 6 or 9 cm. below the surface. A nest of 
this species was examined at Cedar Lake, Washington Co., july 
13, 1903. The. only cell in it was inhabited by a Coelioxys-\a.rva. 
and not a trace of the leaf-cutter larva could be found. The 
parasitic larva in this case closely resembled the newly hatched 
larva of Ccelioxys lucrosa described above, and it passed 
through its first moult on July 16 with the same results as in the 
other case. On August 12, it pupated, and the bee Ccelioxys 
rufitarsis emerged September 4. 
A nest of Megachile latimanus, another species nesting in the 
ground was visited by the parasitic bee Ccelioxys rufitarsis 3 
times on the afternoon of July 13, 1903, also at Cedar Lake. The 
following day it was opened. It contained an unfinished cell 
with an egg of the parasite, 2-| mm. long but no egg of the host- 
bee. This egg of Ccelioxys rufitarsis hatched July 17, giving a 
duration of the egg stage of 4 days. The larva died before moult- 
ing on July 23. 
Through this nest I became acquainted with the mode of ovi- 
position of Ccelioxys which is quite unique in its way. With the 
sharp and rigid end of its abdomen the bee pierces the inner 
layer of leaves forming the cell, and into the slit thus formed it 
forces the egg. (Fig. 4b.) The latter is not of nearly equal 
width throughout as the egg of the average bee, but broadens 
