THE ARGENTINE ANT IN RELATION TO CITRUS GROVES. 51 



Lady-beetles often occur in large numbers on trees overrun by ants. 

 This was commonly the case in Louisiana with a minute, shiny black 

 iady-beetle, Microweisia misella Lee, which occurs in large numbers 

 on trunk and branches of orange trees at certain times of the year. 

 This insect apparently feeds upon eggs and young of the chaff and 

 purple scales and is entirely oblivious of the ants. The same is true 

 of the large twice-stabbed lady-beetle, Chilocorus bivulnerus Muls., 

 which often occurs in large numbers in all stages upon heavily ant- 

 invaded trees. 



In California, large numbers of adult Hippodamia convergens 

 and Coccinella calif omica and all stages of the black lady-beetle 

 (Rhizobius ventralis) occur at times on orange trees overrun by ants. 

 On one occasion more than 1,000 adults of the first two and the 

 ashy gray lady-beetle (Olla abdominalis Say), all of which feed ex- 

 tensively on the excretions of the black scale, were counted upon 10 

 trees on which the ants were exceptionally numerous. Again, more 

 than 60 of the black lady-beetles were found upon each of a number 

 of young orange trees overrun by ants. A certain click-beetle, 

 Limonius subauratus Lee., 1 which feeds upon this excretion, is also 

 fearless of the ants. 



MEANS OF DEFENSE OF THE PREDACIOUS PYRALIDAE. 



The principal means of defense of the larvae of the predacious 

 Lepidoptera which feed upon soft scales and mealybugs consists in 

 moving the body rapidly from side to side like the cracking of a 

 whip. The larva of Laetilia coccidivora Comst., however, protects 

 itself chiefly by means of a tubular web which it spins over itself and 

 its prey and through which ants can not pass. The nearly mature 

 larva? are protected rather effectively also by the spines on their 

 bodies, and several times have been seen moving among numerous 

 ants, apparently hunting for a place to pupate, without being mo- 

 lested. 



MEANS OF DEFENSE OF THE SYRPHIDAE. 



The larvae of aphid and mealybug feeding syrphids also often 

 are found on the leaves and fruit among the ants. The ants, though 

 once or twice they have been found with very young larvae of an 

 unidentified species of syrphid in their possession, apparently never 

 disturb them under ordinary conditions. The immobility and the 

 spines of those species which have been observed working among 

 aphids and mealybugs among ants appear to protect them adequately 

 from the ants. 



1 Identified by Mr. J. A. Hyslop. 



