THE COLEOPTERA 



109 



In the South and also in the West Indies and Mexico are species 

 of Elaterids {Pyrophorus spp.) which have an oval, yellowish spot near 

 each hinder corner of the pronotuni (Fig. 100), and also an area on the 

 underside of the abdomen close to, and partially concealed by the meta- 

 thorax, which are luminous, producing an intermittent, greenish-yellow, 

 quite brilliant light, making the insects very noticeable at night. They 

 are beneficial, the larvse feeding on white grubs. 



The injurious members of this family are those wireworms which feed 

 on seeds and the roots of plants, and there are many kinds which have 



this habit. Some attack wheat; others 

 corn, and still others feed on cotton, 

 grass, potatoes, sugar-beets and other 

 crops, doing much damage. Some are 

 "^ ^ v[ ! most abundant in heavy soils containing 



Fig. 99. Fig. 100. 



Fig. 99. — Adult Eyed Elater (Alaus oculatus L.), about natural size. (From Linville 

 and Kelly, General Zoology, Ginn and Company, Publishers.) 



Fig. 100. — A Luminous Elaterid {Pyrophorus sp.) showing luminous spots on sides 

 of pronotum. Natural size. (Original.) 



much vegetable matter, while others prefer high, sandy land. So many 

 species of wire-worms are injurious and so unlike are their habits in 

 different parts of the country that each kind seems to require treatment 

 especially adapted to it. 



Control. — Some general factors in control may, however, be suggested. 

 When wireworms are abundant in low, poorly drained land, drainage 

 will be of much assistance. When they attack grass roots in great 

 numbers, it is desirable in cultivating such places to substitute field peas, 

 buckwheat, or some crop not closely related to grass, for the first crop, if 

 possible, even though this does violence to the general ideas of crop 

 rotation. When sod land is to be planted, plowing it in July and cultivat- 

 ing often and deeply the rest of the summer will destroy many of the 

 insects. In the South and in arid regions, however, the insects go deeply 



