1 6 JOURNAL OF SCIENCE. 



THE HUMBLE-BEE IN NEW ZEALAND. 



BY GEO. M. THOMSON, F.L.S. 



Among the numerous interesting- and remarkable cases of 

 naturalisation, or, as it is somewhat improperly called, acclimatisation 

 in this colony, none surpasses in its interest and far-reaching results 

 that of the humble-bee. For many years the agriculturists, espe- 

 cially of the South island, had been under the necessity of annually 

 importing all the supplies of Red Clover seed which they required, so 

 to obviate the continually recurring expense and to ensure the pro- 

 duction of a valuable seed within the colony, the Canterbury Acclima- 

 tisation Society was induced to import humble-bees. With the steps 

 taken to accomplish this object, I have not to do at present, though a 

 brief history of this part of the undertaking would, no doubt, be 

 interesting. 



At the very outset, however, a mistake seems to have been made, 

 which shows how much in the dark many of those are who guide the 

 community in acclimatisation matters, and how largely chance often 

 bulks in the final results of such experiments. Eed Clover (Trifolium 

 2)ratense) differs from White Clover {T: repens) and many other papi- 

 lionaceous flowers in having its nectar secreted at the base of a tube 

 9 to 10 mm. (about fths. of an inch) long, formed by the cohesion of 

 the nine inferior stamens with each other and with the claws of the 

 petals. Instead, therefore, of an insect being able to thrust its trunk 

 down to the nectary by the two small openings which lie, one on each 

 side of the superior stamens, as in White Clover, it must insert it 

 directly down the staminal tube. Only in this way can the insect 

 receive a dusting of pollen, and so ensure cross-fertilization of the 

 flowers, without which this. species is practically sterile. "In order 

 to reach the honey in this way, an insect must possess a proboscis at 

 least 9 to 10 mm. long."* This fact was probably not known to any- 

 one in New Zealand when the importation of humble-bees was 

 decided upon. Only the fact was known that humble-bees were the 

 principal agents in fertilizing red clover, and in sending for these 

 insects, the species which is probably the most abundant in England, 

 viz., Bombus terrestris, was selected. According to Midler, who is the 

 best authority on the subject, B. terrestris does not enter the flowers of 

 red clover in a legitimate way and so bring about cross-fertilization, 

 but always makes a hole near the base of the flower and sucks the 

 nectar through this. Its trunk is not more than from 7 to 9 mm. 

 long, so that only the largest females could reach the base of the 

 flower. On the other hand, it is the case in Germany at least, that 

 no less than twelve other species of Bombus or humble-bees having 

 trunks varying from 10 to 15 mm. in length, legitimately visit and 

 fertilize the red clover. Of course the pollen and stigma of this 

 flower are accessible to all insects which are heavy enough to press 

 down the keel, and if bees visit the flowers for pollen only they will 

 no doubt bring about cross-fertilisation. This may account for an 



*"The Fertilisation of Flowers," by Prof. Hermann Miiller. 



