ANNUAL REPORT, 1929 3'51 



Flies emerged from 92 per cent of the pupae confined in slightly moist 

 sand and loam, and from 80 per cent of those in moist sand and loam, 

 but from only 50 per cent and 33 per cent of those in wet loam and dry 

 sand, respectively. Due to climatic conditions the flies emerged from 10 

 to 14 days earlier than in 1928. This condition continued through the 

 summer and resulted in the emergence of thirteen third generation adults, 

 the first observed at Waltham. 



Preliminary studies were made with potted carrots grown from seed 

 treated with mercury compounds. Where calomel was dusted on the soil 

 as well as the seed, the plants showed 35 per cent less injury than plants 

 from untreated seed. Plants from Semesan treated seed showed very 

 little infestation. 



Studies were made of the effect of different sprays on the adult flies. 

 The relation of planting dates to percentage of injury by first generation 

 larvae was also studied as well as relative susceptibility of different 

 varieties. 



Mulch paper effectively checked the first generation infestation, but 

 the second generation damage Avas from 5 to IT per cent greater under 

 the paper. 



Studies were made with insecticides and repellents. Some of the 

 materials showed considerable promise, although the protection from sec- 

 ond generation attack was somewhat less pronounced. 



Systematic Study of Oil Sprays. (H. T. Fernald). The entomological 

 part of the project during 1928-29 has been restricted mainly to confer- 

 ences with the Department of Chemistry which is cooperating in the pro- 

 ject, in order to keep in touch with the work done and to obtain a thorough 

 understanding of the chemical processes made use of. It now seems 

 probable that some of the materials desired for field tests may be avail- 

 able for this purpose the coming spring, and these tests will be made by 

 the Department of Entomology. 



FARM DEPARTMENT 

 Enos J. Montague in Charge 



Intensive Grassland Management under the Hohenheim System. (E. J. 



Montague, C. H. Parsons and R. C. Foley). In the spring of 1928 an 

 experiment in intensive grassland management, under the Hohenheim 

 System, was put into operation. This originated in Germany during the 

 World "War and has since been used successfully in the Netherlands and 

 the British Isles. It is designed to provide a luxuriant growth of grass 

 rich in protein, thereby making it possible for the dairy farmer to pro- 

 duce on his own farm most of the feed necessary for his herd, at least 

 during the summer months. On the College farm this system has 

 greatly reduced the amount of concentrates fed in the summer and has 

 yielded an average return per acre of $69 a year from the plots to which 

 complete fertilizer was applied, as compared with an average return of 

 $22 from the unfertilized plot. 



The Hohenheim System is based upon four distinct principles-: division 



