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 
lady-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 bivulnevus 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 
(RhizoMus 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 
larvae 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. 
