18 BULLETIN 647, U. S. DEPARTMENT OF AGRICULTURE. 



quent occurrence of living soft scales or of remains indicating that 

 such had occupied these shelters is evidence that they generally were 

 built while the ants were attending these scales and had no relation 

 to the armored scales which they covered. 



The forced conclusion is that any protection afforded the armored 

 scales by the ants must be incidental and due merely to their pres- 

 ence on the trees and their very manifest habit of attempting to 

 prey upon all insects not supplying honeydew with which they come 

 in contact. For this protection to be so effective as to be of great 

 economic importance the scales must have enemies so efficient as 

 usually to keep them greatly reduced. The fact is, however, that 

 these scales are not kept under reasonable control by their enemies, 

 even in orchards where there are no ants. 



Paeasites and Predators of the Armored Scales of Citrus in Louisiana. 



Although there was not time for a thorough study of the enemies 

 of the armored scales of citrus in Louisiana, great batches of scale 

 material from ant-free orchards have failed to produce more than a 

 sprinkling of internal parasites. The more common hymenopterous 

 parasites, reared from purple and chaff scale material selected because 

 of the frequency of exit holes, were Aspidiotiphagus citrinus Craw, 

 and Coccophagus flavoscutellum Ashm. 1 A small black lady-beetle, 2 

 Hyperaspis signata Oliv., with wing covers marked with a spot of 

 red about the middle of each, feeds upon these scales to some extent, 

 and a still smaller ladybeetle, Scymnus puncticollis Lee, is suspected 

 of it. Larvae, pupae, and adults of a large coccinellid, Chilocorus 

 bivulnerus Muls., frequently are found in large numbers upon trees 

 overrun by ants, and a minute black species, Microweisia misella 

 Lee., 3 also often occurs on some of the trees by the hundreds. Both 

 of these insects are suspected of feeding upon the early stages of the 

 armored scales, but neither of them seems to be deterred greatly by 

 the ants. At all events, they are found in considerable numbers on 

 trees infested by the ants. 



Influence of the Ant on Abundance of Armored Scales in Louisiana. 



In addition to prolonged field observations on the relations of the 

 ants to the armored scales, experiments were conducted for the same 

 purpose by excluding the ants from certain trees and noting the 

 effect of their presence or absence on the scales. Thus the ants were 

 excluded from one of two vigorous young orange trees having an 

 approximately equal infestation of the purple scale and allowed free 

 access to the other. Notes were made at intervals on the number of 



1 Identifications by Dr. L. O. Howard. 

 * Identified by Mr. E. A. Schwarz. 

 •Identified by Mr. H. S. Barber. 



