108 PROTECTION OF PLANTS, 1915-16 



them to turn yellow and sometimes to shrivel. They multiply very rapidly, 

 but are usually, partially at least, held in check by lady beetles, and other 

 insects. 



Army-worms. 



Army -worms are the caterpillars of "miller" moths, and are very closely 

 related to the common cutworms. 



There are usually two broods of the Army-worm each season. The 

 winter is passed as half-grown caterpillars which mature in May, and the 

 adult moths appear early in June to lay eggs on grass leaves for the second 

 or summer brood of caterpillars which reach maturity in July and which 

 often do much injury. The caterpillars or worms usually feed at night, con- 

 sequently fields may be ruined before their presence is known. Moths emerge 

 in August, and again in October. The following diagram shows the chief 

 points in the life-history of the Army-worm. Since the female moth lays 

 about 700 eggs it is easy to see how rapidly the numbers increase, and the 

 necessity for migration from field to field to get food. 



Serious Army- worm invasions occurred in Ontario and Quebec in 1895 

 and in 1914, and from a study of the climatic conditions of these years it 

 would appear that they are more abundant in a wet spring or summer 

 following a dry season. 



Army-worms may be controlled by (a) plowing three or four furrows in 

 front of the advancing army and killing the worms that fall into the furrows; 

 (b) poisoning a strip a few yards wide on the threatened side with the poison- 

 ed bran mash, such as is used against the grasshoppers, and (c) plowing the 

 fields in late fall. 



Wireworms. 



Wireworms are the grubs or beetles known as click beetles or "skip- 

 jacks." They are slender, yellowish, wire-like grubs, 1-2 to 1 inch long, 

 mostly vegetable feeders and living in the ground. There are several species 

 of wireworms, but they have very similar life-histories. In general the 

 beetles emerge from the ground in May and lay their eggs in grass land, on or 

 close to the crown of the roots. The young grubs feed and grow all summer, 

 and do not mature until July and August of the third year. Then they 

 change to pupae, and a month later into beetles, but the latter do not 

 appear until the following May. 



Wireworms develop mainly in sod land and require practically two years 

 to complete their life. The following preventive measures are valuable: 



