Wireworms 



The Pupa 



The pupal stage (Fig. 15, Plate I) is spent in an oval cell in the soil. 

 The figure represents the pupa on the beetle shown in Figure 16, Plate I. 



The Beetle 



The beetles of this group are characterized by the freely moving joint 

 between the thorax and abdomen and by their power to spring into the 

 air when placed on their backs. 



Our most common species 5 (Fig. 16, Plate I) is dark brown. Figure 

 17, Plate I, represents a smaller, lighter colored species. The drawing 

 to the right of the colored figure is the natural size of this beetle. 



LIFE HISTORY 



The life history of the soil-inhabiting species of wireworms is very 

 similar to that of the white grubs. The eggs are laid in the soil. 

 Usually meadows, pastures or other grass covered lands are selected by 

 the females as places to deposit their eggs. 



Two or three years are required for the worms to reach maturity. 

 Feeding takes place each season. When mature the worm forms an oval 

 cell in the soil in which the change to the pupal stage takes place. This 

 change occurs during the summer months. In the course of a few weeks 

 the adult beetle emerges from the pupa. 



Most of the newly transformed beetles remain in the soil until the 

 following season. However, a few leave their pupal cells soon after 

 emerging. During the following winter these beetles hibernate under 

 dead leaves, crop refuse or other material which furnishes suitable pro- 

 tection against the cold and moisture. 



NATURAL ENEMIES 

 Ground Beetles 



Wireworms are unusually free from attack by parasitic insects, but 

 the predacious ground beetles destroy many of them. Several species 

 of the Genus Calosoma, one of which is represented in Figure 2, Plate 

 IX, Page 27, and their larvae, feed freely on this pest. 



Birds 



Many species of birds are very effective in destroying the beetles. 

 The ill-famed crow is a noted wireworm destroyer. The food of the 

 California shrike, or butcher-bird as it is sometimes called, is known to 

 consist largely of adult wireworms during certain seasons of the year and 

 where these are abundant. From 90% to 95% of the food eaten is 

 composed of these beetles at such times, according to observations 

 recorded by John E. Graf, in Bulletin No. 123, Bureau of Entomology, 

 U. S. Department of Agriculture. 



Skunks 



Skunks, which are so effective in the destruction of white grubs, 

 devour large numbers of wireworms as well as the adult beetles. In 

 1914 the writer examined a quantity of excrement of the little, spotted 

 skunk. No evidence of any other animal food aside from insects was 

 found. Over 10% of the insects eaten were wireworms and click-beetles. 



(°) See explanation of "Reference Figures." page 2 



54 



