90 SEVENTEENTH Report STATE ENTOMOLOGIST OF MINNESOTA—1918 
Experiments in passing cggs through bolting cloths gave the following 
results : 
No. 0 standard bolting cloth passed 11 eggs taken from ordinary 
wheat flour and retained 1 which was attached to some coarse material. 
No. 1 bolting cloth—3 eggs were retained, 4+ passed through 
readily, and 3 others were forced through without injury. 
No. 2 bolting cloth—retained 5 coated eggs, and 1 naked egg was 
forced through endwise. 
No. 3 bolting cloth—no eggs were passed through without injury. 
The experiments with the larvae gave the following results: 
No. 0000 bolting cloth—larvae of all instars passed through. 
No. 000 bolting cloth—larvae of the first five instars passed 
through readily, 7 larvae of the sixth instar crawled through by exert- 
ing some force. 
No. 00 bolting cloth—1 larva of the sixth instar passed through 
with great difficulty. Larvae of the fifth instar also required some 
effort to get through the meshes. 
No. O bolting cloth—retained 1 larva of the fourth instar while 
3 larvae of this instar and 3 of the fifth instar passed through, the lat- 
ter with much effort. 
No. 1 bolting cloth—1 larva of the fourth instar passed through, 
all others of this and succeeding instars were retained. The younger 
larvae all passed through. 
No. 2 bolting cloth—2 larvae of the fourth instar passed through 
with great effort. Smaller ones passed through and the larger ones 
were retained. 
No. 3 bolting cloth—2 larvae of the third instar passed through 
with great effort, all others of this instar were retained. 
No. 4 bolting cloth—3 larvae of the third instar succeeded in 
passing through. 
No. 5 bolting cloth—3 larvae of the third instar passed through 
with effort as before. 
No. 6 bolting cloth—1 larva intermediate between the second and 
third instars, passed through, 6 larvae of the second instar were re- 
tained. 
No. 7 bolting cloth—retained 2 larvae of the second instar and 5 
passed through after a struggle. 
No. 8 bolting cloth—1 larva of the first instar succeeded in getting 
through, while all others were retained. 
It is evident that larvae may pass through any bolting cloth coarser 
than No. 6 and that No. 9 must be used to be absolutely safe. This 
