Based on the context and the answer, generate a question. 

Context: But first I had to trim away some of the shrubs growing up around the window frames . I trimmed other brush , too , because I was out in the yard working , anyway . Foul white flies and other winged pests flew up around me as I worked . I found a nest yellow - jackets in a hole by the apple tree , and killed them .

Answer:

I did n't want to get stung .



What was the reason for killing the pests ?