In wheat, stem sawfly unable to cause destruction of crop due to 

A major cause for large scale destruction of crop plant and crop produce is insect and pest infestation. 

Insect resistance in host crop plants may be due to morphological, biochemical or physiological characteristics. 

1)Hairy leaves in several plants are associated with resistance to insect pests, e.g, resistance to jassids in cotton and cereal leaf beetle in wheat. 

2) In wheat, solid stems lead to non-preference by the stem sawfly 

3) Smooth leaved and nectar-less cotton varieties do not attract bollworms. 

4) High aspartic acid, low nitrogen and sugar content in maize leads to resistance to maize stem borers.