Nov. 5, 1921 Biology of Embaphion muricatum 333 



number of the larvae in the cages were also attacked by an obscure bac- 

 terial disease. This appeared to be identical with that described by 

 Prof. Swenk {12). There would appear somewhere upon the body 

 sutures small circular or irregularly shaped dark brown spots, and these, 

 after a few days, would become larger, until in some instances they 

 would cover one-third to one-half of the body surface. This disease 

 usually caused the death of the larvae within varying periods of time. 

 Larvas found under normal field conditions are sometimes found to be 

 affected both with Metarrhizium and with the disease. 



CONTROL 



While no extended series of experiments relative to control of the 

 insect thus far has been found possible, yet the information secured on 

 the subject has been sufficient to assure the practical value of the measures 

 here recommended in reducing or preventing damage. 



A systematic rotation of crops is one of the most effective procedures 

 in cutting down dam.age. The maximum injury always may be found 

 upon those areas where the ground has been cropped to wheat continu- 

 ously for several years, whereas the minimum injury is found where 

 com, kafir, milo, and other crops are grown which require some degree 

 of cultivation during the growing season. An important factor in migra- 

 tion and infestation lies in the fact that the beetles are wingless and 

 therefore become dispersed much more slowly than do winged forms. 



A number of fields within infested areas, which were also infested by 

 the corn earworm {Chloridea obsoleta Fab.) and other insects of somewhat 

 similar habits, were plowed by farmers during late fall or early spring to 

 destroy the pupae, and it was found that such measures were of consid- 

 erable value in control of the false wireworms in the soil. The pupal 

 cells were crushed and the pupae buried or thrown out upon the surface, 

 where they were exposed to the elements and to predatory enemies. 



It is not only good farm practice but also advantageous as a control 

 measure to destroy and remove from infested fields and adjacent fence 

 rows all clumps of Russian thistles and other weeds or heavy growths of 

 grasses likely to shelter these beetles. 



While adults in small numbers are known to feed upon poisoned bran 

 mash and similar preparations, experiments in poisoning the larvae were 

 not satisfactory. It appears doubtful that such poisoning will ever 

 prove of practical value in dealing with this pest. 



Late sowing of wheat in the fall also has been tried as a possible control 

 measure, but does not appear to be successful unless the season is a very 

 dry one, and even then if the seed has to lie in the ground any appreciable 

 length of time before rain and germination much injury is likely to result, 

 for the larvae are most active in the dry, loose soil under such conditions. 

 65769°— 21 4 



