598 
MILKWEED 
honeybees — only A. syriaca and A. mexi- 
cana, indeed, have been reported as caus¬ 
ing much loss. In the case of these spe¬ 
cies the bees probably seldom perish ex¬ 
cept when several legs or other parts be¬ 
come entangled .at the same time. More 
often the activity of the bee is crippled by 
the many clips and pollinia attached to its 
tongue, legs, or antennae. Butterfly-weed 
{A. tuberosa ) and purple milkweed {A. 
purpurascens) are butterfly flowers. 
In South America Araugia albens, an¬ 
other member of the milkweed family, at¬ 
tracts hosts of moths to its sweet-scented 
flowers. The tongues of the moths are 
caught in the slit-like notches, and as they 
are unable to free themselves they die a 
lingering death. Some years ago it was 
seriously proposed by an economic entomol¬ 
ogist to employ this plant in the extermina¬ 
tion of the codling moth, so injurious to ap¬ 
ples. But this well-laid scheme went agley, 
as the moth would not visit the flowers. 
The way in which the pollen masses are 
clamped to the feet or legs of insects is 
of much interest to beekeepers, and every 
season there are many inquiries in regard 
to this queer phenomenon. The five an¬ 
thers stand close together, forming a 
sheath around the stigma. Each anther is 
provided with two lateral wings; and where 
the wings of two adjacent anthers touch, 
there is a nan-ow slit, larger at the base 
than at the top. The anther, it will be 
recalled, usually consists of two sacs con¬ 
taining the pollen. But in the milkweed 
the grains of pollen are not separate, but 
are bound together in waxy flattened masses 
called pollinia. Two of these pollinia, or 
club-shaped masses of pollen, belonging to 
two different anthers, are attached by flex¬ 
ible bands to a small dry membrane, or disc, 
midway between them. In this flat triangu¬ 
lar disc there is a wedge-shaped slit at one 
end. The disc stands directly back and 
above the slit between the two anther wings. 
This is the pinch-trap ready for action. 
Let us now observe what happens when 
a bee alights on the flower in search of 
nectar. In its efforts to obtain a foothold 
on these small smooth flowers it thrusts a 
claw or leg into one of the slits between the 
anther wings. Presently its leg is drawn 
upward into the wedge-shaped slit in the 
little membranous disc, which soon becomes 
firmly clamped to its leg, or in some cases 
to one of its antennae. The harder the bee 
pulls, the tighter does the little pinch-trap 
hold. When it flies away to another flower 
the pollen masses which, as described above, 
are joined to the little disc by straps, are 
forcibly torn from their pouches. Exposed 
to the air the strap-like stalks dry and 
draw the pollinia close together. Then as 
the bee alights on another flower they are 
easily thrust thru the slit between two of 
the anther wings; but once inserted, and 
the insect’s leg drawn upward, they can 
not again be withdrawn. The bee can ob¬ 
tain its liberty only by breaking the con¬ 
necting bands. If this happens, the pollen 
masses are left in a chamber near the stig¬ 
ma, and the bee bears away the membran- 
Pollen of the milkweed attached to a bee’s foot. 
ous disc with its empty stalks. Disc after 
disc may thus become attached to an insect 
until it is crippled or helpless. 
It is stated on the authority of Gibson 
that one season an English beekeeper lost 
thousands of bees from the effects of strings 
of these clips. It was at first supposed that 
they were being destroyed by a fungus. 
Many different explanations have been 
given of these curious structures by per¬ 
sons not familiar with the flowers of the 
milkweed. Some think them a parasite, 
others a protuberance growing on the bee’s 
foot, and others a winged insect enemy of 
the bee. We give here an engraving of this 
curiosity, magnified at a, and also a mass 
of them attached to the foot of a bee. If 
the insect is not strong enough to pull out 
the pollinia, or later to break the connect¬ 
ing bands, then it perishes slowly of star¬ 
vation, probably with little pain. These 
dry membranous discs are often described, 
even in botanical works, as glands, or as 
being glutinous or sticky, but this is not 
the case. 
Climbing Milkweed ( Gonolobus laevis). 
