%\\t Canadian ^ntomola^bt. 



Vol. XLVI. LONDON, DECEMBER, 1914 No. 12 



BEES VISITING HELIANTHUS. 



BY. T. D. A. COCKERELL, BOULDER, COLORADO. 



The genus Helianthus, consisting of the annual and perennial 

 sunflowers, is native only in America, though widely cultivated in 

 the Old World. The common sunflower, H. annuns, is wholly 

 sterile with its own pollen, and has to be visited by insects in 

 order to produce seed. Presumably the same is true of the other 

 species of the genus. The insects carrying the pollen are various, 

 but the bees are far more important than all the rest combined; 

 their incessant activity can only be appreciated by one who has 

 worked with sunflowers throughout the summer. 



At Goodview, Colorado, August 2, 1913. I took a census of 

 insects on flowers of cultivated H. annum (var. coronatus) for a 

 short time, with this result: Andrena helianthi, 12; Halictoides 

 marginatus (perhaps some were Halictus) , 9 ; Halictus armaticeps, 

 4; Melissodes, 2 cT, 1 9 ; Panurginus innuptus, 1; Apis mellifera 

 liguslica, 1; Syrphid, 1. These were recognized as they flew, but 

 on July 18, I collected a series of bees from the same flowers, at 

 the same place, and found I had Andrena helianthi Rob., Halictus 

 armaticeps Cress., Halictoides marginatus (Cr.), Panurginus 

 innuptus (Ckll.), both sexes, Melissodes aurigenia Cress., 9, 

 M. confusiformis Ckll., 9, and Megachile agustini Ckll., d". 



The domesticated honey-bee, belonging to the Old World 

 genus, is here an insignificant factor in sunflower pollination. 

 Mr. Collins of Boulder, who has many hives of bees, informs me 

 that they do not go to sunflowers unless the supply of other nectar 

 runs short. When they do make honey from sunflowers, it is 

 very yellow. 



The most important sunflower bee, with us, is certainly 

 Andrena helianthi. In some localities it is probable that the 

 species of Megachile, which work fast and carry a lot of pollen, do 

 more work. M. helianthi Ckll. was collected by Rohwer on the 

 Avild sunflower (Helianthus annuns lenticularis) at Boulder, Colorado. 



