1908.] PUBLIC DOCUMENT No? 73. 225 



I saw more than a hundred small boxes of this foreign material come 

 by mail to the Saugus laboratory in one day. This material is collected 

 in various parts of Europe, and may contain few or many parasites of 

 several very different kinds, and these may be accompanied by their own 

 enemies in the form of secondary parasites. Thus the greatest care 

 and expert attention are needed to properly handle this foreign material. 

 I noted that very fine wire screens were used in all open windows, and 

 the others were tightly closed with paper pasted over all cracks. All 

 doors shut tightly, so that every precaution is taken to prevent the 

 escape of undesirable material from the building, if by any chance it 

 should get out of the cages into which it is placed soon after it arrives. 



The many thousands of brown-tail hibernating nests which come 

 from Europe by express in winter are placed in tight boxes, and thou- 

 sands of parasites emerge and find their way into glass tubes inserted 

 into one side of the box. All secondary parasites are carefully separated 

 out and killed, and the true parasites liberated in badly infested locali- 

 ties. Many of the living larvae from these winter nests are bred in 

 cages, and when nearly full grown a different parasite develops which 

 breeds freely in American larvae in cages, and is thus allowed to mul- 

 tiply before being turned loose in the field. 



During June and July hundreds of boxes containing later stages of 

 brown-tail larvae and gypsy caterpillars come by mail from several 

 European countries. These are opened inside a small show-case ar- 

 ranged with armholes through the sides. Two men wearing tightly 

 fitting sleeves and rubber gloves open the boxes through the armholes 

 in the case, and by looking through the glass top of the case they can 

 separate out the parasites and any living larvae without any danger of 

 their escaping. The tight sleeves and rubber gloves are necessary to 

 protect one from the brown-tail hairs, which cause an irritating " rash.'' 

 Many Tachinid flies and their larvae and pupae are found in these boxes 

 of caterpillars from Europe. These parasites are placed in breeding 

 jars, where they are kept till the flies mate and the larvae and pupae 

 develop into the flies. After the flies mate, most of them are taken into 

 badly infested localities and turned loose, while some of them are kept 

 in large field cages or houses in which gypsy and brown-tail caterpillars 

 are living. 



The living caterpillars which are found in the European material 

 are placed in cages and fed, with the resiilt that more Tachinid flies 

 are obtained and some Hymenopterous parasites, among which are 

 some very promising enemies of these pests. Most of the parasitic 

 material coming from these European caterpillars is carefully nurtured 

 and multiplied in small cages on American gypsy caterpillars and be- 

 lated or retarded European brown-tail larvae from the winter nests, and 

 it is finally turned loose in promising localities in the field. 



A little later the European material consists largely of the pupae of 

 the brown-tail and gypsy moths, and from these emerge Tachinids and 

 Pimpla parasites, which are just in time to attack the retarded European 



