ATTRACTING QUEENS 12; 



In some nests I tried a longer course of treat- 

 ment, but found that after about three weeks' 

 confinement, sometimes less, the colony ceased to 

 thrive, and signs of degeneration began to appear, 

 the larvae failing to grow to full size and delaying 

 to spin their cocoons. The particular cause of this 

 trouble was not ascertained, but it may be that the 

 larval food contains something that is gathered in 

 the fields besides honey and pollen, or that the 

 workers are unable to prepare this food properly 

 without exercise. It was noticed that a small colony 

 throve better and longer in confinement than a 

 populous one, and that the pollen-storing species 

 lapidarius and terrestris were less quickly affected 

 than the pocket-maker, latreillellus. A weak colony 

 of sylvarum was confined twice with good results. 



In the domiciles occupied by lapidarius colonies, 

 as soon as the workers became busy and the queens 

 ceased to fly I reduced the size of the hole in the 

 mouse-excluder so that it would also exclude the 

 parasite Psithyrus rupestris. To deter wax-moth 

 and Brachycoma I relied upon balls of naphthaline, 

 placing two or three of these in the grass close to 

 the mouth of the hole and eight or ten around the 

 wooden cover, but I found that these did not keep 

 out the little Phora vitripennis. 



I was pleased to find that the loss of nests in my 

 artificial domiciles, though great, was, so far as I 

 could ascertain, much less than that which occurred 

 in nature. In the proximity of my domiciles I had 

 discovered five nests commencing in natural holes, 



