1904.] 



The Asparagus Fly. 



499 



In a few days, or, according to some authorities, in a fortnight 

 to three weeks, the larvae hatch out and bore into the tender 

 stalks and young shoots. The maggots work directly down the 

 stem, and their presence is marked by yellowish galleries or 

 tunnels ; these last are often too deeply seated to be seen 

 without dissection. Pupation takes place from June onwards, 

 according to the time of egg-laying, but is practically over by 

 August. It is considered probable that there may be two 

 generations in the year. The pupae hibernate in the under- 

 ground portion of the stem. 



The affected shoots become brownish or yellow in colour, and 

 are stunted and decomposed, rotting finally below the ground 



a. Male. b. Female, both magnified (after Taschenberg). 



or at the point where they emerge from the soil. They occa- 

 sionally show a bluish colour. 



Treatment. 



1. Where the area to be treated is small and easily examined, 

 good results may follow if small rods dipped in a sticky sub- 

 stance are stuck in the ground early in spring. The flies will 

 settle on these and be caught. 



2. The flies may be collected early in the morning when they 

 are resting on the tops of the asparagus shoots. 



3. Taschenberg recommends sprinkling the tops of the shoots, 

 when the dew is on them, with powdered charcoal ; this deters 

 the flies from egg-laying. 



4. In the summer all injured stems should be cut away and 

 burned. In autumn all remaining stems showing larval tunnels 

 and all dry stumps should be dug up and burned, so that injury 

 in the following year may be lessened or prevented by the 

 destruction of the pupae. 



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