64 SOUTHERN FIELD CROPS 



western part of the wheat-growing region. Its injury is 

 done by sucking the juices from the plant. Its natural 

 enemies among insects are relied on to keep the green-bug 

 in subjection. One of these, a lady-bug beetle (Fig. 10), 

 has sometimes been propagated by entomologists and sent 

 into the infested regions. 



In the shock, stack, or bin the wheat grain is attacked 

 by weevils and by the larva, or worm stage, of the small, 

 gray grain-moth (Galechia cerealella) (Fig. 22) . The reme- 

 dies consist in prompt threshing of the grain and in placing 

 near the top of the tight bin of threshed grain one pound 

 of carbon-disulfide for each 30 bushels of grain. This 

 liquid promptly vaporizes. The vapors are destructive 

 to insect life. They are also quite inflammable, so that no 

 fire, or light, or smoking is permissible about the granary 

 while grain is being thus fumigated. 



LABORATORY EXERCISES 



The young plants. 



(1) Repeated tests should be made of the student's ability to 

 distinguish the young plants of wheat, oats, barley, and rye by the 

 auricles (Figs. 1, 12, 23, and 28). If no young plants are available, 

 leaves of mature plants may be used for the same purpose, after 

 dampening them. 



(2) Select five young wheat plants, each having abundant 

 space around it, and record (a) total number of stems and (6) 

 average number of stems per plant. 



(3) Repeat exercise (2) with five plants closely crowded by 

 other plants. Compare figures for (2) with those for (3). 



(4) Plant 25 kernels of wheat at each of the following depths : 

 | inch, 1 inch, 2, 3, 4, 5, and 6 inches. Keep the soil moderately 

 moist ; at intervals of a week record the number of plants that 

 have come up from each depth of planting. 



