NOTES ON THE MIGRATION OF THE HESSIAN 



FLY LARVAE* 



BY 



JAMES W. McCOLLOCH 



Assistant Entomologist in charge of Staple Crop Insect Investigations 



AND 



H. YUASA 



Assistant in Life History Studies, Kansas Slate Agricultural Experiment Station 



CONTENTS P AGE 



Introduction 307 



Methods of Study 309 



Observations 310 



Eggs 310 



Hatching of eggs 310 



Orientation of the larva 310 



Migration of the larva on the leaf 312 



Rate of migration 313 



Variations in the rate of migration 317 



Behavior of the larvae on migration 317 



Variations in behavior 319 



Mortality of larvae on migration 320 



Influence of moisture 321 



Influence of light and darkness 321 



Discussion and Conclusions 321 



Summary 322 



Literature Cited 323 



The migration of the Hessian fly (Mayetiola destructor Say) 

 larva on the leaf where it hatches to its feeding place between 

 the leaf-sheath and the stem is one of the most critical periods 

 in the life history of the insect, yet the literature on this point 

 in the life economy is very meager. Packard (1883, p. 213) 

 makes the following statement: ' as soon as the footless larva 

 or maggot hatches, it makes its wav down the leaf to the base 

 of the sheath." Osborn (1898), fhorne (1902), Felt (1902), 

 Webster (1906 and 1915), Forbes (1910) and many others simply 

 recapitulate the brief statement quoted from Packard. 



Enock (1891, pp. 333-334) made some interesting observations 



on this point. He states that " the female fly, as a rule, lays 



1 Contribution from the Entomological Laboratory, Kansas State Agricultural 

 College, No. 26. This paper embodies the results of some of the investigations 

 undertaken by the authors in the prosecution of project No. 8, Kansas Agricul- 

 tural Experiment Station. 



307 



