COMMON VETCH AND ITS VARIETIES 
13 
compared with flowers not bagged. The results of these experi- 
ments are shown in Table 5. Pods were readily formed in the paper 
bags, in the tarlatan cages, and outside, both when the flowers were 
tripped and when not tripped. However, the percentage of flowers 
setting pods when inclosed either in the paper bags or tarlatan cages 
was less than when they were left in the open under natural condi- 
tions. Of the flowers in the tarlatan cages tripped and not tripped, 
there was an increase in the percentage of pods set when the flowers 
were tripped. It seems apparent that the flowers are highly self- 
fertile but that tripping may have some slight effect in aiding fertili- 
zation. It is also apparent that inclosing the flowers in tarlatan 
cages and paper bags decreases to some extent the number of flowers 
setting pods. 
Table 5. — Pollination studies of vetch varieties, showing the relation of flower 
tripping to seed setting 
Plants inclosed in tarlatan cages 
Plants not inclosed in tarlatan cages 
Tripped 
Not tripped 
Not bagged 
Bagged 
Varietal 
Number 
of— 
O 
Number 
of— 
CO 
— 
O 
Number 
of— 
CO 
O 
Number 
of— 
O 
name 
ft 
a 
G 
P 
a 
CO 
o 
+3 
T3 
'£ 
CO 
-u 
3 
CO 
3 
CO 
w 
CO 
"o 
2 
to 
CO 
cs 
CO 
O 
CO 
o 
X 
CO 
a> 
CO 
w 
as 
a 
0) 
1 
o 
i 
o 
CO 
O 
C 
cS 
O 
CO 
5 
o 
o 
O 
o 
>H 
fc 
fa 
h 
fa 
fa 
fa 
>* 
fa 
fa 
fa 
fa 
fa | fa 
P.ct. 
P.ct. 
P.ct. 
P.ct. 
Leucosperma . 

286 
226 
79 
313 
214 
68 
2 
68 
68 
100 
52 
27 
52 
Macroearpa... 
7 
142 
113 
79 
144 
112 
78 
3 
39 
38 
97 
46 
18 
40 
Erythrosper- 
ma . 
5 
125 
117 
93 
166 
142 
85 
2 
61 
59 
96 
52 
27 
52 
Melanosper- 
5 
6 
356 
343 
330 
310 
92 
90 
432 
408 
359 
285 
83 
70 
2 
3 
118 
113 
106 
112 
89 
99 
92 
92 
56 
58 
61 
Oregon.. 
63 
Alba.. 
5 
3 
194 
176 
169 
160 
87 
91 
341 
168 
252 
144 
74 
85 
2 
2 
57 
51 
53 
48 
93 
94 
63 
60 
43 
26 
68 
Carnea 
43 
Nemoralis 
1 
14 
14 
100 
36 
32 
88 

Total.. . 
1,636 
1,439 
88 
2,008 
1,540 
78 
507 
484 
95 
457 
255 
54 
It is indicated by these experiments that insects that may trip the 
flowers are not essential to seed setting, though they may be some- 
what beneficial. Crossing in common vetch does not seem to take 
place, and the benefit from tripping, if any, probably is that of a 
mechanical stimulus. 
INSECTS VISITING FLOWERS OF COMMON VETCH AND ITS VARIETIES 3 
All varieties of Vicia sativa are rather free bloomers and nectar 
producers. The flowers are generally attractive and are easily worked 
by most insects in search of nectar or food. The stipules secrete 
substances that are collected and used by insects as food, and the 
presence of aphids draws numerous ladybird beetles, hover flies, and 
ants to the vetch plants in search of secretions or of the aphids 
themselves as food. 
The following insects have been found actively engaged in working 
on Vicia sativa plants: Honeybees (Apis mellifica) ; bumblebees, many 
species; ladybird beetles, many species; flies, many species; hover 
3 This discussion is based solely on observations made by the junior writer at Corvallis, Oreg. 
