126 Biolofpj arul Kronomic Significance ry/'Tipiila paludosa 



The experience here recorded has been general for a series of 

 years; large numbers of Tipiila larvae have been regularly obtained 

 from lea fields upon farms on Deeside and elsewhere in the neighbour- 

 hood, which during the periods tested had no crop losses due to their 

 attacks. In a good many such cases the numbers obtained from single 

 fields were considerable. A case where serious damage was effected 

 is given upon page 132. 



♦ 



Fig. 3. Plan of Craibstone Home Farm. 

 Experimental Field, No. 5. 



Summarising the outstanding features of this record we note: 

 (1) An apparent scarcity of larvae in spring before ploughing took place. 

 The failure to find Tipula was not as subsequent finds proved due to 

 their smallness of size, and it does not seem likely that they were deeply 

 situated in the soil at this time. They have rarely been found below 

 six or eight inches under the surface. Tests made wath deep cages in 

 winter (Feb. and March) yielded only insignificant numbers (eight 

 per cent.) below six inches from the surface. 



(2) When known to be present in the field they could not be found 

 in the act of attacking the crop. The suggestion that they feed at 

 night is plausible, but observations on larvae in cages have shown that 

 they feed readily at all times. The fact that there was an abundance 

 of humic matter in the soil is probably not without significance in this 

 connection (see pp. 127 — 8). 



