MEXICAls^ BEAN BEETLE — WHITE 351 



the United States, as the parasites and predaceous insects occurring 

 in the United States are of little value in keeping this insect in check. 

 In 1921 H. F. Wickham collected near Mexico City, Mexico, a dipter- 

 ous parasite of the bean beetle. In 1922 E. G. Smith, engaged by the 

 Federal Bureau of Entomology, found a tachinid parasite of the 

 larval stages of the bean beetle abundant at Mexico City and ship- 

 ments were made of several hundred parasitized bean beetle larvae 

 to Birmingham, Ala. This parasite was recognized as new and de- 

 scribed by J. M. Aldrich as Paradexodes epilachnae in 1923. The 

 l^arasite did not survive the winter in the Birmingham, Ala., area, 

 nor become established after liberation in the field. It was thought 

 that a more intensive study of the parasite and its host in Mexico 

 might yield information which would insure its successful introduc- 

 tion in the United States, and in 1929 B. J. Landis was detailed to 

 make such a study at Mexico City. Between July 1929 and October 

 1930, 60,000 puparia were shipped from Mexico City to Columbus, 

 Ohio, and a serious attempt to colonize the parasites in the areas of 

 the United States infested with the bean beetle was begun in 1930. 

 Attempts to store larvae, adults, and puparia of the parasite through 

 the winter months at Columbus, Ohio, were not successful, and a 

 breeding stock was maintained from August 1930 to September 1935 

 by breeding the flies in the laboratory. Of the 145,500 adult parasites 

 bred at Columbus, 82,000 were released in 19 States, including States 

 from Alabama to New York in the East and Texas and New Mexico 

 in the Southwest. The numbers of flies released in separate colonies 

 ranged from 100 to 4,000 individuals and many of these colonies were 

 restocked for several consecutive years. In most cases the parasites 

 were found to have become established during the current season. 

 However, in no instance has this parasite been definitely collected 

 from colonies released the previous season, and consequently it must 

 be concluded that the attempts to introduce this parasite were not 

 successful. Many workers and observers have contributed informa- 

 tion to our knowledge of the large array of parasites and predators 

 found attacking the bean beetle in this country, but in the aggregate 

 these natural enemies are of no great importance. This list includes, 

 beside insect parasites and predators, bacteria and fungi, as well as 

 a few birds and mammals. 



Climatic factors. — The general climatic conditions of the eastern 

 States have permitted the spread of the beetle over practically the 

 whole region east of the Mississippi River. On the other hand, ob- 

 servations and studies have shown that there are certain areas within 

 this region where the insect has been in general a more consistent 

 pest than elsewhere. Roughly, this area may be designated in the 

 Appalachian Range from the southern part of Ohio southward to 



