BREEDING PLACES 57 



of the pits of " ant lions," which have much the same 

 requirements. 



On the little Isle of Lula, where fly was found in 1918-19 

 to be so numerous that the catch was at the rate of 56*5 

 males per boy-hour, there is nowhere for the fly to deposit 

 larv£e except in *' loci " — there is no sand or gravel beach 

 anywhere on this rocky little island. 



This figure however is exceptional, but I have no doubt 

 in my own mind that palpalis can exist in considerable 

 number on a coast line where there are only scattered 

 " loci " in which to place its larvae. 



The next point to be considered is shade, which is of 

 great importance. The pupa is dependent upon protec- 

 tion from the sun, although, as I have shown above, it 

 can survive a certain amount of exposure. 



Shade for pupae may be either permanent or variable. 

 Permanent shade is afforded by (1) caves or large rocks 

 undercut at the base ; (2) prostrate tree trunks arching 

 over the ground ; (3) hollows at the base of or among 

 roots of living trees ; (4) the pent-house roof formed by the 

 disc of earth torn up by the roots of an overturned tree ; 

 (5) thick bushes. 



I have not found caves to be nearly as productive as 

 I had expected ; on Kimmi Isle, where flies were caught 

 at the rate of 33 males per boy-hour, pupae could only be 

 found at the rate of 6-7 per boy-hour. On the other 

 hand, at a locality on Wema where the fly rate was 59-5 

 per boy -hour, jnipae were found at the base of an under- 

 cut rock at the rate of 72-4 per boy-hour. I think the 

 soil in caves is almost too dry. 



Prostrate tree trunks arching low over the ground 

 form ideal sites for pupae, and the one illustrated was a 

 favourite collecting ground on Bugalla, On the same 

 beach on Bugalla and close to it was a tree much hollowed 

 at its base, which is figured ; it proved to be a very good 

 collecting ground for pupae. 



