CLOVER CULTURE. 125 



rapidity. According to Thompson (Insect Life, volume 4, page 157) 

 they have so greatly increased that he asks whether they may not 

 become a serious pest to the apiarist, as they work on all sorts of cu'ti- 

 vated flowers. 4 



In order to reach the honey an insect must have a tongue from .3543 

 to .3937 inches (9 to 10 millimeters) long. The honey lies from .2755 to 

 .3937 inches (7 to 9 millimeters) deep. Any insect sufficiently heavy to- 

 press down the keel can pollinate the flower. Bumble-bees are, of 

 course, the common pollinators. Prof. Osborn informs me that he has 

 observed two common species (Bornbus Pennsylvanicus and B. fervidus). 

 My friend, Mr. Robertao* , records several m^re. The honey bee can,, 

 no doubt, pollinate red clover, as they often collect pollen. I have 

 taken an interest in bees for many years, and have given some attention* 

 to red clover and honey bees. The following paragraph from a paper 

 published in 1888 may be of interest : 



" In the summer of 1883, in the vicinity of La Crosse, Wisconsin. I 

 noticed large numbers of honey bees on the flowers of red clover. In 

 many cases they were actively collecting pollen, but in some cases honey r 

 through perforations in the corolla made by some other insects. Her- 

 man Mueller says the honey bee 'usually visits the red clover only for its- 

 honey, which its proboscis is not able to reach in the legitimate manner 

 yet I have now and thon seen hundreds of honey bees on a patch of 

 red clover, all busy collecting pollen.' Here at Ames I, have seen rect 

 clover visited by several butterflies, especially the large red but'erfly 

 (Danais archippus) , cabbage butterfly (Pieris rapae), the yellow butterfly 

 (Coleus philodice) , also C. eurytheme, and a fly (Bombylius). Red clover is- 

 adapted especially to bees, but Dr. Hermann Mueller of Germany, and 

 Mr. Robertson, of Carlinville, Illinois, record a larg number of butterfly 

 visitois. Thirteen out of twenty visitors belonging to the butterfly 

 family were observed in Illinois. There is no question that they doocca 1 

 sionally pollinate red clover and effect cross fertilization. Mr. Robert- 

 son writes: 'Bumble-bees depress the keel so that their heads and 

 proboscides are well dusted with pollen, but butterflies can insert their 

 thin tongue* without depressing the keel, and even if they get a little 

 pollen on their thin proboscides, it is apt to be wiped off by the closely" 

 approximated tin of the petals, which close the mouth of the flower." 



Th. Pergande expresses the belief that different species of thrips,, 

 which are found in many kinds of flowers, may effect cr^ss pollination 

 (Psyche, volume 3, number 100, page 381). Prof. Osborn informs m& 

 that two kinds of thrips are common in clover blossoms, Thrips tritici and 

 Phloethrips-nigra, but these certainly cannot generally effect cross fer- 

 tilization. 



Can the honey Lee effect cross fertilization in mammoth clover 

 (Trifolium medium) ? It probably can do so as it does in the common 

 red. I have not studied the flowers of mammoth clover carefully, but so 

 far as I can see, the flowers of the forms in the Colleare collection are 

 about the same size as red clover. One form has much smaller heads a^d 

 the flowers are also somewhat smaller, but I am inclined to think that 

 mammoth clover is pollinated principally by bumble-bees. 



The work of honey bees in fertilizing white and alsike clover is welfc 

 known ; in fact, they can easily accomplish this. One other thought 

 suggests itself to me in this connection. I believe it is generally sup- 

 posed that the second crop of clover produces more seeds than the first. 

 This I t" ..ik is duo to insects, there being a much larger crop of bumble- 

 bees at the time of the second bloom than at the first. 



Our readers, even those who have the least familiarity 

 with scientific terms, will, with the foregoiiig 1 explanation, be 



