572 



IOWA DEPARTMENT OF AGRICULTURE 



visitor is not understood, but it is altogether unlikely that they are 

 familiar with the purpose of the intrusion or are aware that it will mean 

 more hungry mouths for them to feed. 



After a hasty study of the insects that were collected from a number 

 of flowers at our state experiment station last summer, I have con- 

 cluded that flowers should be divided into three general groups as re- 

 gards their insect visitors: First, those with nectar at the base of 

 elongated tube and accessible only to butterflies and to bees larger or 

 longer-tongued than honey bees — the bumblebee flowers; second, those 

 with shorter tubes and nectar accessible to honey bees, but not to the 

 majority of short-tongued bees, ants and flies — the honey bee flowers, 

 third, those that are not at all exclusive but expose their nectar to all 

 comers — the fly and ant flowers. I wish to consider these three groups 

 separately. The insects illustrated represent the species seen upon and 

 collected from flowers of a typical plant of each group. These collec- 

 tions make no pretense toward being complete, though they do represent 

 considerable time and study and, I think, s'how the facts pretty well. 



I chose red clover as a type of Class I (Fig. 6), the long-tubed flowers, 

 partly because of its abundance and partly because of its economic im- 

 portance. It is a well known story how the red clover when introduced 

 into Australia absolutely failed to mature seed until bumblebees were 

 taken to that country. Now bumblebees are plentiful, and large crops 

 of clover seed are produced. Notice that the honey bee, at the right end 

 of the flrst row (Fig. 1), is the smallest of the visitors — the rest of them 

 being large solitary bees, bumblebees, butterflies and moths — the elite 

 of the insect world. The other hosts of nectar-loving insects have noth- 

 ing to draw with and the well is deep. Indeed the honey bee, which 

 seems rather out of place here, is generally rare in its visits, although 

 considerable numbers of them were seen during the dry weather of 

 August, when the scarcity of other picking induced our little friends to 

 undertake the heroic. 



Fig. 6. 



Flowers of Red Clover (TrifoUum pratenseQ. 1, 2, 3, flowers from below, 

 showing k, keel ; w, wings, c, standard ; 4, 5, wings ; a, calyx ; m, stamen ; 

 I, style. Honey bees cannot get this nectar because it is out ot reach of the 

 tongue of the insect. (Mueller.) 



