106 GENERAL ZOOLOGY 



deserving of mention ; but the female goes a step further 

 and makes sure of a supply of seeds for the larva by col- 

 lecting pollen from the stamens and thrusting it into the 

 pistil. The advantage to the larva is obvious, since its 

 supply of food is rendered certain ; the advantage to the 

 plant probably lies in the fact that not all the seeds thus 

 provided are eaten by the larva before reaching maturity. 

 This association may be cited as an illustration of symbiosis. 

 As mentioned under the topic of bumblebees, these bees 

 are very largely responsible for pollenizing the red clover. 

 The honeybee is an important partner of the apple, pear, 

 blackberry, and raspberry, aiding them by insuring polli- 

 nation. In the milkweed flowers the pollen is borne in 

 V-shaped packets. As a wasp or a bee visits a flower to get 

 the nectar, the pollen masses become attached to its feet 

 and are carried away by the visitor. The structure of the 

 milkweed flower is such that when the insect visits another 

 flower the packages of pollen attached to its feet slip into 

 grooves which bring them into contact with the pistils, thus 

 insuring fertilization of the flower. The pollen masses in 

 some instances become so firmly attached that the insect 

 is held prisoner. The early cultivation of Smyrna figs in 

 this country was unsuccessful. It finally became known 

 that small wasps essential for pollinizing the flowers were 

 lacking. When these insects were introduced into Califor- 

 nia, the fig industry became established. 



