504 ANNUAL EEPORT SMITHSONIAN INSTITUTION, 1925 



Mr. Edwards experimented amongst aphids on willow and plum, 

 all small and naked species, with three caterpillars in the second, 

 third, and fourth stages that he had received from Miss Morton. 

 He laid the smallest larva on a willow leaf directly bj^ a small clus- 

 ter of aphids at which a few ants were engaged. The caterpillar 

 paid no heed to the aphids, but walked past and back and forth and 

 was on both sides of the leaf. The ants were somewhat inquisitive, 

 but did not trouble the caterpillar, nor were they disturbed by it. 

 This went on for about 15 minutes, when he removed the larva. 



He put the next sized larva (second molt) on the same leaves, 

 and the ants were agitated and ran about gesticulating, but paid 

 more attention to their cows than to the larva. He put this larva 

 on a plum leaf by a large colony of aphids at which were a dozen 

 black ants. The ants sprang at it, bit at it everywhere, especially 

 trying to get a hold under the edge of the body where the surface 

 is naked, or at the joints of the segments, or at the second segment 

 Avhich, being bent over the head, is more exposed than any other 

 segment. One determined fellow seized on the second segment and 

 was hardly to be dislodged, was at last by a violent jerking of the 

 head, but wounded the larva so that blood flowed. When the attack 

 was at the joints the larva squirmed so as to tighten the joints just 

 there. These attacks were simultaneous and by at least six ants 

 at a time. The larva crawled awa}^, and the assailants mostly 

 dropped off. 



He then put the largest larva (third molt) amongst the same 

 excited ants, and they attacked it in the same manner, but seemed 

 Imable to make an impression on it. The hairs protected the whole 

 upper side more sufficiently. The caterpillar crawled up and down 

 over the leaf, followed by some of the ants which attempted to seize 

 it at every vulnerable part. But no harm was done. He repeated 

 the experiment the next day and came to the conclusion that the 

 willow ants were mild tempered, and seemed unlikely to hurt a 

 larva; but that the black ones were fierce and would attack when- 

 ever they saw the enemy. 



He suggested that perhaps the butterfly avoids the fiercer ants 

 and the aphids which they guard, and, therefore, is not to be looked 

 for on certain plants. 



Though exhibiting great hostility toward the caterpillars the ants 

 do not destroy the eggs. The butterflies do not pay any attention 

 to the ants, nor do the}'^ disturb them. 



Enemies. — So far as is known this butterfly has no parasites, and 

 nothing is known to feed upon it. 



Once with a knife blade I was dislodging a fully grown cater- 

 pillar from a mass of aphids when it was struck by a large reduviid 



