THE ARGENTINE ANT IN RELATION TO CITRUS GROVES. 23 



cloth was tied about the branch on which 3 mealybugs still remained 

 on the ant-infested tree to mark their location, and the persistence 

 of mealybugs in this tree after June 12 was due to their being 

 sheltered by this cloth. The instinct for hunting shelter is much 

 stronger in the young mealybugs than in any other of the soft scales 

 and doubtless results from their being the preferred food of preda- 

 tory insects. 



During the course of the foregoing experiment on orange trees the 

 mealybugs on the bearing fig trees, under constant attendance by the 

 ants, had increased gradually, and during May overflowed their 

 hiding place in the crevices of the bark and began to infest some of 

 the smaller branches and leaves. On the branches they formed small 

 groups and infested a considerable number of leaves, spreading along 

 the underside, mostly in singles, twos, and threes. The period of 

 maximum infestation of the fig trees extended from about the middle 

 of May to the latter part of July. On June 26, while at its height, 

 six of the trees were banded and the ants excluded for a period of 98 

 days, or until October 2, while six others were left unbanded and 

 used as checks. 



The work of the enemies and parasites had become evident by the 

 middle of June, however, and it was apparent that the mealybugs 

 were having a struggle to make further headway. By about the 

 middle of July they had begun to lose ground, and from that time 

 very rapidly disappeared from all unsheltered portions of all trees, 

 banded and unbanded alike. The mealybugs very rarely, if ever, 

 succeed in reaching maturity on fig leaves, even on ant-infested trees. 

 A heavy parasitization was indicated early in July, due principally 

 to a small, yellow-brown hymenopterous parasite. 1 



After August 15 the few mealybugs remaining on the large fig 

 trees were in protected situations in the bark of the trunk and larger 

 branches. The ant trails also had become thin in the unbanded trees 

 by that time because of the scarcity of mealybugs. As for injury to 

 figs by mealybugs, though a few small groups appeared on some of 

 the fruits of ant-infested trees during this experiment, the per- 

 centage of fruits so affected was so small as to be negligible. Prac- 

 tically all the fruit was clean and bright at picking time. The 



1 This insect (Paraleptomastix abnormis Gir.) measures about 1 mm. long, some speci- 

 mens less ; general color yellow, marked on head, thorax, abdomen, and wings with smoky 

 gray ; the wings with three rows of dusky, broken, transverse stripes near base, middle, 

 and tip, respectively, giving them a spotted appearance ; legs and antenna? very long and 

 slender, the former light yellow, the latter smoky brown. The insect has the peculiarity 

 of keeping the wings elevated and in movement when running about on the leaves, which 

 aids in distinguishing it in the held. The technical description by Girault is given in 

 The Entomologist, v. 48, p. 184, London, 1915. While this parasite has been introduced 

 into California, in localities in Alhambra, Duarte, and Sierra Madre, it has not yet become 

 established as thoroughly there as in Louisiana, but if it does become so it will be an 

 important factor in reducing the ant-attended mealybug infestations in that State. 



