ANIMALS WITH JOINTED 



nies there are as many as 27 different types 

 of individuals, not all present at once but 

 occurring at some time during the history 

 of the colony. Each type performs certain 

 duties and fits into tlie harmonious opera- 

 tion of this complex venture. 



Ants seem to have followed the food hab- 

 its of man, at least in their methods of pro- 

 viding a food supply. The more primitive 

 ants merely feed as carnivores, but pastoral 

 ants take aphids into their nests and feed 

 them, gathering the honeydew (an excre- 

 tory product) from them in repayment for 

 their efl^orts. The harvester ants show fur- 

 ther development by carrying cereal grains 

 into their burrow to supply them with food 

 during the winter. Finally, the most ad- 

 vanced are those ants which gather a cer- 

 tain species of fungus and plant it in under- 

 ground gardens, tending it even to the point 

 of adding humus as a fertilizer. Such be- 

 havior represents a very complex interrela- 

 tionship of instincts, to say the least. 



Experiments seem to indicate that insect 

 behavior consists entirely of instincts built 

 up thi'ough millions of generations. Instincts 

 are inherited behavior patterns. They are 

 presumably inherited like other traits, and 

 subject to the laws of natural selection. 

 In order to speak of intelligence among in- 

 sects, there would have to be evidence not 



Fig. 11-40. Some insects, such as certain braconid 

 flies (not a fly but a relative of the honeybee), lay 

 their eggs inside the body of other insect larvae as 

 show^n here. The large sphinx-moth caterpillar in this 

 case supplies the food for the developing fly larvae, 

 which finally break through the skin and spin their 

 white cocoons. The attack usually means death to the 

 caterpillar. 



only of memory but of ability to choose, 

 and while there is a little of the former in 

 some species, the latter has never been 

 observed. Complex integrated patterns of 

 instincts which make an animal fit perfectly 

 into its environment are oftentimes mis- 

 taken for intelligence, but careful analysis 

 will show that such an interpretation is not 

 justified. 



In the reproduction of insects, fertiliza- 

 tion is internal. Most insects lay eggs ( ovip- 

 arous) and deposit them in a place where 



Fig. 11-41. Insects lay their eggs in a variety of places. The katytid (Microcenfrum) digs a deep hole in the ground 



where she deposits her eggs. Note the long ovipositors. 



