1931] The Age of Insects 25 



know they make selections in foods, and we say bees smell because 

 they seem to be able to distinguish members of their own colony from 

 other bees, and they seem to be able to recognize their queen and to 

 distinguish drones. 



The sense of sight in insects is taken care of by two distinct types 

 of eyes, the simple eyes and the compound eyes. The former we be- 

 lieve is used chiefly to distinguish light from darknees while the latter 

 is used to give an image. The compound eyes of insects are composed 

 of from a few to many hundreds of hexagonal prisms, called ommatid- 

 ia. It is believed that each ommatidium forms a portion of the 

 image just as tiles are put together to form a mosaic. Or, since the 

 ommatidia are hexagonal in shape, perhaps we can best compare the 

 image that insects receive to the image our eyes receive when we look 

 through a piece of glass which has been laid down on poultry netting. 

 Each mesh of the poultry netting would contribute its portion to the 

 image just as each ommatidium of the insect's compound eye does. 

 Obviously such an eye is better adapted to seeing motion than it is 

 to seeing distinct images. 



Insect Psychology. 



I wish I had the agile mind and the facile pen of a Fabre so that I 

 would be able to unfold for you some of the beauties of the instincts 

 of insects. We may see striking illustrations on every hand. Why 

 do certain insects always lay their eggs in such situations that their 

 young will find an abundance of food at hand? This question is of 

 course easy to answer in the cases of those insects whose adults feed 

 on the same plants as the young. It is simply a matter of placing 

 them in the most convenient place; but we are confronted with the 

 query, why do some of these insects take such elaborate pains to con- 

 ceal their eggs by placing them in the stems of plants or imbedding 

 them in the tissues of the leaves? On the other hand we are confronted 

 by that vast host of adult insects which lay their eggs on food plants or 

 animal hosts upon which they themselves do not feed. Or we are con- 

 fronted by that compHcated set of reactions, so well illustrated by our 

 solitary wasp, where a nest is constructed and prey is searched out and 

 stung in the precise spot to paralyze the individual but not cause its 

 death. Then the prey is dragged back to the nest and stored with 

 an egg and the nest closed and concealed. Or we see an insect like the 

 cornfield ant taking the eggs of the corn and cotton root louse into its 



