33 



observed, all the eggs laid by this female hatched and the young 

 reached maturity, the adults being males without exception. 



To summarize these observations, unfertilized eggs hatch and 

 the larvae develop into adults of the male sex. Two females were 

 known to lay forty-four and one hundred and twenty-nine eggs re- 

 spectively, and in both cases many more were undoubtedly laid. 

 These same insects lived in the adult condition for twenty-three and 

 more than thirty-six days respectively. 



I have tried several times to isolate a female which had cer- 

 tainly been impregnated, but was unsuccessful. It is not impossible 

 to do this, however, and I suspect that when this is done the young- 

 produced from fertilized eggs will all develop into females, giving us 

 a condition similar to that which is generally believed to occur in 

 the honey bees, and known as arrhenotoky. 



In regard to the length of adult life, I might further add that in 

 greenhouses where there are millions of live adults on the plants, it 

 is difficult to find a single dead specimen on the benches, providing 

 they have not been killed by artificial means. This is a further indi- 

 cation that natural deaths among adults are rare, and that the adult 

 life of each individual may extend over many weeks. 



Should it prove true that unfertilized eggs of this insect produce 

 only males and fertilized eggs only females, then the number of adult 

 males and females will be in direct proportion to the number of un- 

 fertilized and fertilized eggs. In Psyche (April, 1903) I gave an 

 estimate of the proportion of the two sexes of Aleyrodes in nature, 

 based on actual count of eighty-five specimens of adult Aleyrodes 

 taken at random, representing four different species. The figures 

 given were twenty males to sixty-five females. For the purpose of 

 obtaining a more exact idea of the. proportion of the sexes in the 

 present series I counted one hundred adults taken at random, and 

 found twenty-three males to seventy-seven females. 



The spreading of the adults from greenhouses probably accounts 

 for the presence of this species on out of door plants in most cases, 

 but there is no reason to suppose that it cannot pass the winter out 

 of doors in the egg state as do other species of the genus in this 

 region. 



