[ 164 ] 

 t 



Larvak collected in Lower Deeside and Lower Donside (continued). 



Data for 1919. 



1562 



7245 



8807 



17-6 



As is indicated in the foregoing table no infected larvae were obtained 

 between May 16tli and June 21st. This was the case in other areas in the 

 north of Scotland of which several were examined. 



The fall to 0-6 per cent, at the beginning of May, and the complete absence 

 of infected larvae in the soil for nearly five weeks, we attribute to the fact 

 that the Bucentes maggots had pupated, and thus the Tipula larvae then 

 found were such as had escaped infection by the parasite. 



Larvae obtained at Craibstone on June 21st showed an appreciable per- 

 centage infected by Biicentes larvae, and from that date until July 7th, when 

 the oats had grown too high to allow of further search for grubs, infected 

 larvae continued to be obtained in high percentages, as is shown in the table. 



Number of Parasitic Larvae per Host. 



Observations made in 1918 show that one, two, three, and even four 

 parasitic maggots may occur in one host. This was also the case in specimens 

 found in the early months of 1919. A noticeable feature among the larvae 

 found in the later part of 1919, viz. from June 21st onwards, was that there 

 were seldom fewer than two Bucentes maggots in each host larva, 5-6 being 

 common, and in one case as many as nine Bucentes maggots were found in a 

 single host. 



Size of Parasitic Larvae found. 



Larvae from 1*5 mm. up to 8-5 mm., which represents the maximum size, 

 have been found. 



Even within the same host, the larvae may differ in size. For example, 

 two maggots, 5 mm. in length, were found in the same host along with two 

 others of 3 mm. In one case, where nine parasites occurred together, these 

 were all 3 mm. in length. It seems more probable to us that these differences 



