268 



JOURNAL OF ECONOMIC ENTOMOLOGY 



[Vol. 15 



Successful development has not been observed at a temperature below 

 60° F. Eggs withstood 31° F., March 29. The highest daily mean 

 temperature during summer (U.S. Weather Btu-eau Record) was 88° F., 

 August 1. • 



The num-ber of eggs in a mass ranges from 5 to 76, with an average 

 of 52.7 eggs in a group, calculated from 207 groups. The largest number 

 of egg m asses laid by a single female was 34 comprising 1,669 eggs . Of 1 , 69 1 

 beetles, 51.45 per cent, were males and 48.55 percent were females. 



Fertile eggs were obtained from females collected in hibernation and 

 isolated, showing that fertilization in the spring is not necessary. 



Dispersion 



Flight is the most important means of natural dispersion. Marked 

 beetles have been taken 5 miles from the point of liberation in one 

 instance and 3^4 miles in two instances, as table 2 shows. 



Table 2. — Records of Flight of Mexican Bean Beetles 



'Liberation was made at 720 feet above sea level. 



'In two instances, collections were made in opposite directions. 



'Others observed but not collected. 



Crossed hills 800 to 1,150 feet above sea level. 



Insect Enemies and Natural Control 



In addition to the hst of species already published, the following have 

 since been determined from field observations as enemies of Epilachna 

 corrupta : The lepidopterous larvae, Prodenia ornithogalli Gnen., Laphygma 

 Jrugiperda S. & A. and Heliothis obsoleta Fab., and the diadem assassin 

 bug {Sinea diadema Fab.). These species were fed a restricted diet of 

 bean beetle larvae and pupae in confinement, and two species matured. 

 In the insectary and some of the field cages the ants, Solenopsis geminata 

 Fab. and Pheidole sp., destroyed pupae. 



None of these species is of much value in natural control. 



