42 PROTECTION OF PLANTS, 1918-19 



In a short time I was able to capture five males and one female oiAndronicus cylin- 

 drus, eight males oi Clinodon Anthophorateminalis, nine males of Megachile sp. 

 and one female of Halictus leronxii. 



The mothers once fertilised begin the work of constructing the home for 

 their ofTspring. The same locality serves the purpose every year. The soil is 

 very light, composed of fine sand and unsuitable for any sort of cultivation. As 

 a rule the afternoon between 3 and 4 o'clock is the time chosen to begin the task of 

 digging the burrow. The front tarsi and perchance the mandibles loosen the 

 soil, passing it back to the middle tarsi, which in their turn pass it on to the hind 

 tarsi. The work is eagerly pushed on. The insect works vertically, sideways, 

 and even on its back so as to dig to more advantage. Soon the hole deepens; in a 

 quarter of an hour the insect disappears and the work now goes on unseen. The 

 tarsi gather the soil together and pass it back behind the abdomen. When a 

 sufficiently large load has been collected, the Colletes reascends the narrow cor- 

 ridor, pushing the load up to the surface. This results in little heaps of debris, 

 which put one in mind of a miniature mole hill, and are sure indications of the 

 presence of a nest. 



From time to time at regular intervals, an upheaval agitates the little mound, 

 indicating that a fresh load has been brought up. There is nothing more curious 

 than the aspect of the locality where a colony of Colletes are making their nests. 

 The mounds rise one beside the other, sometimes by hundreds, with their fresh 

 sand recently brought up from the depths nearby. The work continues throughout 

 the night, and I have reason to believe is completed at the end of fifteen hours. As 

 long as it lasts the heap of sand remains closed, for the bee does not go outside the 

 burrow to deposit her load. The work completed, the insect excavates a passage 

 for herself through the debris. This entrance tunnel, curved like an arc, serves 

 so to speak as an antechamber. There the Colletes remains, morning and evening 

 when the temperature is not high enough to invite her out of doors, and all these 

 openings — at the bottom of each one of which a bee is watching — remind one of a 

 stronghold, the least approach to which is jealously guarded. At first I ex- 

 perienced serious difficulties in the task of studying and describing the method of 

 nest construction. Indeed, while endeavouring to follow the course of the burrow, 

 the fine sand kept falling into the tunnel, in proportion as I dug. The idea then 

 occurred to me to pour plaster into the orifice, as if to obtain a mould. I thought 

 this notion an original one, and was quite proud of my invention. But there is 

 nothing new under the sun, for I discovered later that others before me had 

 employed the same method. In any case the method was a complete success, and 

 enabled the construction of the nest to be easily studied. It was a difficult matter 

 it is true, to withdraw a mould without breaking it, but by the use of sealing wax 

 the trouble is easily disposed of. These underground habitations present the 



