700 
SOURWOOD 
THE PARASITIC SOLITARY BEES. 
Notwithstanding that the bees are pro¬ 
verbial for industry beyond any other 
group of insects except, perhaps, the ants, 
there are many parasitic genera which no 
longer gather stores of pollen and nectar, 
but rear their brood at the expense of the 
nest-building genera. They are variously 
called guest bees, brood parasites, inqui- 
lines, or cuckoo bees, while their unconscious 
victims are known as host bees. The guest 
bees are usually allied in structure with 
their hosts, and both are probably derived 
from the same primitive stock. Thus the 
bumblebees ( Bombus ) and the false bum¬ 
blebees ( Psithyrus ) doubtless have a com¬ 
mon ancestry. Common genera of para¬ 
sitic bees are Nomada (parasitic on An- 
drena ), Coelioxys (parasitic on Mega¬ 
chile), Stelis (parasitic on Anthophora). 
(Fig. 5.) 
The manner in which a cuckoo bee enters 
the nest of her host varies greatly with 
different genera. Melecta boldly enters the 
burrows of Anthophora, even when the 
female is present, and the latter seems 
wholly unconscious of the danger. Triepeo- 
lus more prudently waits until her host 
Colletes has departed for the field before 
entering the tunnel. In France, according 
to Fabre, Stelis nasuta opens with great 
difficulty the hardened cells of Chalicodoma, 
sealed with clay cement, lays several eggs 
and again closes the opening with a pellet 
of clay. The American parasite Stelis sex- 
maculata lays her eggs in the nests of Alci- 
damea producta, which are found in the 
stems of the blackberry or sumac. The 
lawful owner Alcidamea lays her egg on 
the top of a conical mass of beebread, but 
the parasite Stelis places her egg near its 
base where it is likely to escape notice. 
There may be as many as four cells, each 
closed with a felt-like mass of chewed 
strawberry leaves. 
Graenicher has observed and described 
the tragic end of the host larva. The larva 
of the parasite is armed with long sharp 
mandibles, but those of the host larva are 
blunt and bifid and not well adapted either 
for defense or attack-—so the latter is 
doomed from the beginning. When the 
two larvse, while feeding on the beebread, 
meet, the parasite seizes the body of the 
host larva between its sharp mandibles. 
The host larva may struggle a little but 
soon succumbs, and after sucking out its 
liquid contents the parasite again turns to 
the beebread. If there are two larvse of the 
parasite Stelis sexmaculata a combat be¬ 
tween them is sure to occur, and the victor 
is the larva obtaining the first hold on the 
body of the other; but two larvae of Alci¬ 
damea can not injure each other. 
The handsomest parasitic bees belong to 
the genus Nomada, and Smith calls them 
the most beautiful of all the bees found, in 
Great Britain. They are often called wasp- 
bees, because of their gay coloring. They 
are dark red in color, often suffused with 
black, and maculated with bright or pale 
yellow. Their larvae are often found in the 
nests of • Andrena. 
In the pollination of flowers the para¬ 
sitic bees are of much less importance than 
the nest-builders. Since they have no oc¬ 
casion to gather pollen, they have largely 
lost their pollen brushes and visit flowers 
only to procure nectar for themselves. A 
part of the species restrict their visjts 
largely to the Compositae which yield nec¬ 
tar freely. 
S OURW0 0 D (Oxydendrum arh oreum ). 
Also called sour gum, sorrel tree, lily-of- 
the-valley tree, and elk tree. A fine tree, 
belonging to the heath family, or Ericaceae, 
growing 40 to 60 feet tall and a foot in 
diameter. The smooth bark is brownish 
red, and the young twigs are light green. 
The leaves are oblong, pointed at the apex, 
smooth on both sides, and have a sour 
taste. The numerous white urn-shaped 
flowers are in slender one-sided racemes, 5 
to 6 inches long, which hang in clusters at 
the ends of the branches. From the re¬ 
semblance of the blossoms to those of the 
little perennial herb of the garden, sour- 
wood is often called lily-of-the-valley tree. 
The popular names sourwood and sorrel 
tree are derived from the sour odor and 
flavor of the leaves and twigs. 
Sourwood grows in rich woods from 
southern Pennsylvania to western Florida 
and southern Alabama, westward to south¬ 
ern Indiana, the Arkansas Mountains and 
western Louisiana. It is most abundant in 
the mountainous tract of country occupied 
by the Alleghenies and the Blue Ridge, but 
