14 BULLETIN 75, U. 8S. DEPARTMENT OF AGRICULTURE. 
MOTHS AND OTHER NIGHT-FLYING INSECTS. 
Owing to the fact that tripped flowers are sometimes abundant 
while day-flying insect Visitors are scarce, it was suspected that night- 
flying insects might be a factor. To secure information on this point 
two series of experiments were undertaken. 
One of these experiments was conducted at Pullman, Wash., in 
1909. Seven alfalfa plants were inclosed in fine-meshed mosquito 
netting. Five of the plants were left under the netting during the 
entire time of the experiment in order to find out what proportion 
of the flowers become tripped when insects were entirely excluded. 
Two of the plants were kept inclosed in netting during the daytime, 
but were uncovered during the night. The results obtained are 
given in Table V. 
TaBLe V.—Alfalfa flowers tripped by night-flying insects at Pullman, Wash., 1909. 
On same plants outside of 
On plants inside of netting. netting: open to insects. 



. | Flowers Flowers 
Plant. plower bearing Plant. bearing 
TOES Al iapods: pods. 
: Per cent. Per cent. Per cent. 
SIN IRI ae PANE SESE oc Se a a ee ce eT I * 0 TAG A NO soe al ase 37.31 
DNS SIE ot a ees ee ops ees SE ese eh Saas ere *0 * 0 NORD seen eee 16.12 
IN ON RE re oP Riis ee eet * 3.92 ESOC TINO WI Ses. eee 56. 60 
INO Woo Sine as past aaa leila a MeN ae ot Sem eae * 3.03 5 OOF RN Oss Osea pean 20. 51 
INO, SV se aCe seers Dee A ete Meee see Sieh Sec ee *0 £1 3G6e SNOs(eeea ee ee 35. 38 
ING R (see see he ot ih Sent ca OE Ne tenn eral T 4.63 TonSel NOs OR eee 30. 35 
TINO Ne Ore ae eT ais Al SNe ors, ere ae ei 7 4.60 7 2.01 

* Inclosed in netting during entire experiment. + Inclosed in daytime; open for night-flying insects. 
A similar experiment was conducted at Chico, Cal. On May 31, 
1909, 400 alfalfa flowers on several different plants were marked and 
observed until June 2. Table VI shows how many flowers were 
tripped during the day or night. 
TaBLe VI.—Alfalfa flowers tripped during different periods of the day and night at Chico, 




Cal., 1909. 
Period covered. Period covered. 
Mice Number ihe Number 
of flowers (in pases 20 Tanta 1 Fen ee of flowers 
From— To— tripped. From— To— | tripped. 
4p.m., May 31.-...-- 7.30 p. m., May 31. 22) |) Lives une ds. .| 2 palit’. aliments 16 
7.30 p. m., May 31...| 5.30 a. m., June 1.. Ol} 2qos me dune) tse 4p.m., Junel.... 18 
5.30 a.m., Junel....| 10 a.m., June ila 23) || 4ap. me une lates 7.320 p.m.,Junel.. 18 
10a.m., ante 0 1la.m., June | IL |} 7.30 p.m.,Junel:.-| 6 a.m. June2-...-- 0 

From the evidence presented in the two preceding tables, as well as 
from the results of observations made at other times and places, it is 
clear that night-flying insects are at most a small factor in tripping 
alfalfa flowers. 
