28 



THE HISTORY OF ECOLOGY 



noxious insects is a primary problem 

 which has long been attacked. One ecolog- 

 ical method uses the natural controls of 

 trouble-making insects. Fungus diseases at- 

 tracted attention at an early date; Forbes, 

 (1895) traced the history of knowledge of 

 such diseases of insects in Europe and 

 America and described in detail additional 

 experiments designed to stop the inroads 

 made by the chinch bug, Blissus leucop- 

 terus, upon farm crops in Illinois. As early 

 as 1880 Thomas had observed a relation 

 between temperature and rainfall and the 

 development of excessive populations of 

 chinch bugs. 



Another phase of insect control, distinctly 

 ecological in approach and in general im- 

 plications, comes from the use of predatory 

 species and insect parasites to attack de- 

 structive species. Sweetman (1936) has 

 summarized the history of such eflForts. It 

 appears that Forskal (1775) gave the first 

 written account of this usage when he de- 

 scribed the introduction of colonies of 

 predatory ants from the nearby mountains 

 into Arabian palm orchards to attack other 

 ants that were feeding on the date palms. 



Sweetman (1936) notes that Erasmus 

 Darwin wrote about the possibilities of bio- 

 logical control in 1800. In 1840 in France 

 large numbers of native carabid beetles 

 were placed on poplar trees to destroy 

 caterpillars of the gipsy moth. The interna- 



tional transfer of parasites to prey on 

 introduced insect pests was suggested by 

 Fitch in 1854 and was put into effect by 

 Planchon and Riley in 1873. Other early 

 experiments of this nature in the 1870's and 

 1880's were almost forgotten in the success 

 achieved, largely as a result of the work of 

 C. V. Riley, by the importation of a 

 coccinelhd beetle from Australia into Cali- 

 fornia in 1889 to control the cottony-cush- 

 ion scale. 



Oscillations between insect pests and 

 their parasites were demonstrated independ- 

 ently by Howard (1897) and Marchal 

 (1897) for different species. Two other 

 workers, (Bellevoye and Laurent, 1897) 

 provided the outline of a mathematical 

 theory of the biological control of popula- 

 tion size. They set up a fairly simple equa- 

 tion to show how such a state, now called 

 a steady state, would be maintained. 



Growth of knowledge about the interre- 

 lations of organisms with respect to 

 mammalian disease also proceeded at a 

 rapid pace in the closing decades of the 

 last century. Herms (1939) records that 

 Josiah Nott of New Orleans published an 

 essay on the origin of yellow fever in 1848 

 in which he expressed the belief "that mos- 

 quitoes give rise to both malaria and yellow 

 fever." This was a fortunate guess. Carlos 

 Finlay of Cuba set forth a similar theory 

 for yellow fever about 1880 and conducted 



Table 1. Important Diseases Known before 1900 to Be Insect-Borne (Data Extracted Chiefly 



from Herms, 1939) 



* Names of other men closely connected with these discoveries, or some of them, can be 

 found in Herms' text and are not repeated here, even though their omission may do an injustice 

 to worthy workers. 



