8 THE GIPSY MOTH AS A FOREST INSECT, 



])robability was supported by delinite conlirmatoiy evidence — ^tliat 

 the failure of the moth immediately to increase was due as much as 

 anytliing to the parasites; and a wholly unexpected and phenomenal 

 rate of parasitism was found to prevail in some localities. Inci- 

 dentally several species of parasites until then unrecognized as impor- 

 tant or promising were found and large numbers were shipped to 

 America. 



The r61e played by the parasites, however, was obviously less 

 important than had been assumed when the work of parasite impor- 

 tation was inaugurated. Grenerally speaking, it appeared that though 

 the mcrease of the moth was prevented or retarded through para- 

 sitism, it was principally if not invariably through disease that an 

 actual outbreak was checked. 



This was borne out by the cu'cumstances associated with two local 

 outbreaks in southern Italy: One in Sicily, in the extensive cork- 

 oak forest of San Pietro, near Caltagirone, and the other in the 

 communal forest of the town of Gioia Tauro, in Calabria. In both 

 of these localities, and particularly in the latter, the parasites were 

 abundant and varied. In neither were they able to prevent the 

 rapid increase of the moth, much less to bring about a decrease. 

 In both the defoliation of a large portion of the forest was absolutely 

 complete, and in neither was the "wilt" disease operative. 



The conditions in the fon^st of San Pietro were the more interesting 

 and mstructive because the invasion there was of no less than 12 

 years' standing. At no time, according to the statements of the 

 local authorities, had the entire forest been defoliated at once, but 

 the mvasion would sweep back and forth over it, so that the trees 

 were defoliated about every second or thii'd year. 



Here m this Sicilian forest all the amazing stories told of the gipsy 

 moth upon the occasion of its historic outbreak in Maiden and Med- 

 ford were abundantly substantiated. There were no streets and 

 very few houses, but there were a few gardens, fields, orchards, and 

 vineyards, and an abundance of mid plants, shrubby and herbaceous. 

 Of them all, wild and cultivated, hardly a dozen species were immune 

 from attack. There were places where at times the ground was 

 black with the caterpillars as they came out of the forest, whicli no 

 longer afforded them either food or protection, and invaded the fields 

 and open spaces. Here the combination of burning sand and blazing 

 sun resulted in the agonizmg death of myriads, and their dead bodies 

 could have been swept up by the bushel. 



Neither in 1911 nor in 1912 was a single caterpillar dymg of the 

 wilt observed. Parasites were abundant each year, destroying 

 approximately 90 per cent, which was far from sufficient to prevent 

 increase. Each year the millions which died of starvation and 



