46 BULLETIN" 647, U. S. DEPARTMENT OF AGRICULTURE. 



ants are dead. Thus about 91 per cent of the mealybugs taken from 

 the ants were dead or discolored and scarcely able to move, while 

 with the black scales and aphids carried the percentage of dead was 

 still higher. On the other hand, of those insects which do not fur- 

 nish honeydew to the ants most are alive when taken from their 

 captors. Nearly all captive white flies are alive, as are the psocids, 

 and even such fragile insects as thrips may be handled so lightly by 

 their captors as to remain apparently uninjured. Thus, on one 

 occasion, a thrips dropped by an ant at once started to run, when 

 another ant seized and bit it viciously several times, after which the 

 only sign of life was a twitching of legs and antennae. 



The ants almost always carry their scale and aphid hosts, as well 

 as all other captured insects, to the nest, which is rarely if ever so 

 situated as to afford living conditions to these insects. On rare occa- 

 sions, in Louisiana, living mealybugs had been found in ant trap- 

 nests, containing only dried straw and manure, but this happened in 

 winter, when the mealybugs left not only the trees where there were 

 ants, but also those in a part of the orchard where no ants occurred, 

 and located on Bermuda grass. The soft scales found in ants' nests 

 almost always have been dead. On one occasion when an exception- 

 ally large number of ants carrying mealybugs down an orange tree 

 could be traced to the nest in the rotting wood, many dead and dis- 

 colored mealybugs and mealybug particles were found and 80 whole 

 bugs counted. There were only 2 living mealybugs, and these ap- 

 peared to be diseased, being unable to move except for twitching the 

 legs a little. 



The ants carry their host insects in considerable number only when 

 these insects are exceptionally numerous, at which times they are 

 able to supply a great deal more honeydew than the ants actually 

 require. In Louisiana the ant attendance on the black scale and the 

 citrus mealybug was nearly always in greater number than could 

 obtain honeydew from them continuously. In California, however, 

 the black scale, where unchecked by fumigation, becomes very numer- 

 ous, overflowing the trees and covering them with sooty mold. On 

 such trees the ants carry many scales at times. Thus in one orchard, 

 in which both ants and black scales occurred in exceptionally large 

 numbers, an unusually large number of ants were so engaged. For- 

 tunately for observation, many of the nests to which ants could be 

 traced were in the rotting stubs of cut branches. In these nests the 

 scale phase most readily seen (that is, shells of mature scales) was 

 scattered throughout the ants' galleries. Many nests, with their 

 contents, were removed and examined, and the remains of numerous 

 insects found there, but the black scales, of which there were 118 

 young stages, all dead, and 97 shells of mature scales, outnumbered 



