J. Eennie 127 



(3) The occurrence of most of the larvae at the surface beneath 

 loosened decaying turf. Their presence here in the spring is general; 

 they occur both loosely below, and also very frequently deeply embedded 

 in the turf. The disturbance of the soil in ploughing and harrowing 

 is probably the cause of their gathering in these situations, and their 

 presence is probably primarily due to the need for shelter and moisture. 



(4) The absence of harmful effect upon the crop notwithstanding 

 their presence in considerable numbers throughout the spring and 

 summer. This feature is considered in connection with the further 

 data given below. 



Further consideration of feeding habits. 



With a view to rendering clearer the feeding habits of the larvae 

 and to throw light upon the circumstances under which they attack 

 growing crops numerous experiments were made of which the following 

 are illustrations. 



I. A small lot of larvae reared from eggs laid in September was 

 kept in ordinary field soil covered with loose turf in a small laboratory 

 cage. No crop was sown in the soil, but it was watered from time 

 to time. They wintered under these circumstances and continued 

 throughout the following summer. The larvae pupated in July and 

 the last of them emerged as flies on the 4th August and mated on the 

 same day. The life cycle in this case occupied about eleven months. 



II. A collection of larvae was kept out of doors in small boxes contain 

 ing ordinary garden soil without growing vegetation during the months of 

 May, June, and July. They survived this treatment, but were under- 

 sized. Some managed to pupate, but others died in the larval stage. 

 One imago was observed to fail in the act of emerging from the pupal 

 case. The larvae of this group did not on the whole do so well as those 

 of lot I, and the mortality towards the end of the experiment was 

 high. Dissections showed the presence of vegetable fibres in the 

 intestine, and a considerable amount of gritty material. It may be 

 mentioned that this latter is normally present in the intestine. 



III. A collection of larvae was kept in small cages with no growing 

 plants, and a limited amount of decaying vegetable matter amongst 

 the soil. These conditions were maintained during the months of 

 May and June of the present year. At the end of June all were alive 

 and healthy looking, and some were well grown. The cages were 

 set in a large field rearing box containing washed sea sand, amongst 



