112 



ELEMENTARY STUDIES IN INSECT LIFE 



have entered the slit, the insect pulls them up into the 

 stigmatic chamber. They will go no farther, and the 

 insect finds itself a prisoner again. If escape is made 

 it is generally by breaking the retinaculum. The in- 

 sect then carries away the corpusculum and part of the 



FIG. 96. Pollen-masses attached 

 to leg of bee. a, central body (cor- 

 FIG. 95. Leg of insect pusculum); 6, band (or retinaculum) 



with small chain of corpus- joining pollen-mass to central body; 



cula. Photographed from c, pollen-mass (pollinium). Drawn 



nature by W. C. Stevens. from nature. 



retinaculum. This serves to catch other corpuscula rest- 

 ing in their natural positions, so that we can frequently 

 find insects that have continued their visits, bearing a 

 whole chain of these corpuscula attached to a claw or 

 some part of the leg. (Fig. 05.) Many insects are at- 

 tracted bv the nectar. It is evident that only the strong 



/ 



favor the plant. The honey-bee is among the most 

 frequent visitors, and no student can remain long among 

 milkweeds in blossom without observing successful cross- 

 pollination or being an eye-witness to a tragedy. 



The Yucca Lily and the Pronuba Moth. The fertiliza- 

 tion of the yucca blossom by a small white moth sur- 

 passes all other modes of cross-fertilization by insects, 

 since the insect is not induced to do the work by tempt- 



