CERTAIN 



BEETLES EAT 



EGGS OF 



COLLOPS 



PREDACEOUS BUGS, WASPS, 



LADYBIRD BEETLES, 



BIRDS 



BIRDS 



THE ENEMIES OF ALFALFA CATERPILLAR 



t 



WILT 

 DESEASE 



SPIDERS 



DRAGON FLIES 

 ROBBER FLIES 



ALFALFA CATERPILLAR 



LARVA 



PUPA 



ADULT 



B. STAGES IN THE LIFE OF THE ALFALFA CATERPILLAR 



I 



DAYS 



1 



15 





.l-^A 



A. ALFALFA, THE BASIC FOOD, GROWTH - HARVEST 



RELATIONSHIPS IMPORTANT IN CONSERVATION. READ UP 

 Fig. 38.10. The relationships of alfalfa plants and the various animals associated 

 with them are an example of the natural control of populations. Change in one 

 population brings changes in others. Knowledge of such relationships is essential 

 for conservation. A, in favorable climates the widely cultivated clover-like alfalfa 

 grows to full size in 30 days. B, the lifetime, egg to adult of the orange and yellow 

 butterflies (C alias philodice eiiry theme) is also about 30 days. In the populations 

 of alfalfa plants and alfalfa butterflies however, there are always various stages of 

 development. The butterflies lay their eggs mainly on young plants. The cater- 

 pillars feed heavily on all the plants. The pupae are fastened to the stems. C, main 

 enemies of the caterpillars and adults. Pupae suffer least. D, the enemies of enemies 

 of the alfalfa pests; each group keeps other groups from the destruction of over- 

 population. (Based on Smith, Bryan and Allen: "The Relation of Flights of Colias 

 to Larval Population Density," Ecology, 30:288-297; U. S. D. A. Bull 124, and 

 personal communication.) 



793 



