Report of Missouri Fwrmers' Week. 



547 



no time differ much in appearance from the mature insects. The 

 dragon flies have only three stages, the second or larval stage being 

 spent in the water. When the growth is completed, the youngster 

 crawls up the stem of some convenient plant and simply unbuttons 

 his coat in the back, so to speak, and crawls out of the old nymph- 

 skin, with a marvelous pair of wings. 



The minute plant lice or aphides are strangest of all in their 

 life histories. The first generation to appear in spring hatch from 

 eggs and all are females. These give birth to living young. Sev- 

 eral successive generations of living young are thus produced until 

 late in the season, when males also appear and eggs are laid from 

 which shall appear the generation of the coming year. 



STAGE OF INJURY. 



Most insects are injurious in the larval stage. Cutworms, 

 which are very injurious as caterpillars, are harmless as moths. 

 There are exceptions to this rule, of course. Mosquitoes are 

 troublesome only as adults. Few insects are injurious in more 

 than one stage. A very few are beneficial in one stage and in- 

 jurious in another. An example of this class may be mentioned, 

 the blister beetles. In the larval stage they are beneficial by de- 

 stroying eggs of other insects, such as the grasshoppers. In the 

 adult stage they sometimes become so abundant as to be injurious 

 to crops, notably potatoes and alfalfa. 



Birds play an important 

 part in destroying many harm- 

 ful insects, especially in the 

 larval stage, although they also 

 take many of the adults. 



THE SEED EATERS. 



The boy who has to pull weeds 

 from the garden when he would 

 like to go fishing, should be the 

 last to persecute the sober-col- 

 ored little field sparrows which 

 live almost wholly on weed 

 seeds. There are several dif- 

 ferent kinds of native American 

 sparrows that thus render in- 

 valuable services. They should 



Fig. 1. Tomato can for Bluebirds and 

 Wrens. 



