146 PARASITES OF GIPSY AND BROWN-TAIL MOTHS. 



that if the larvae were allowed to enter damp earth as soon as they 

 issued from the host, better results might be obtained. In order to 

 provide for this, the style of rearing cage which is shortly to be 

 described and figured, was devised. With its aid we were enabled 

 to secure a large proportion of the parasite maggots within a few 

 moments after they had finally separated themselves from the cocoon 

 which the host invariably spins before dying, and these were given 

 every advantage which could be afforded to assist in the successful 

 completion of their transformations. The results, however, were 

 always the same and not one perfect puparium has been secured. 



The reasons for this may not be far to seek, but the chances are 

 that it will be a long time before an adequate explanation is afforded. 

 When it was found that the larvae failed to pupate under the most 

 favorable conditions, they were carefully examined on the supposi- 

 tion that death might possibly accrue through the action of the pois- 

 onous spines into which they must necessarily come in direct contact 

 in leaving the host cocoon. It was at once discovered that there was 

 invariably a number of minute reddish spots scattered irregularly, 

 and more or less abundantly, over the whole or a part of the body. 

 It looked, at first, as though these spots might be the result of contact 

 with the poisonous spines, but upon further examination it was found 

 that they were of a character which could hardly be attributed to 

 this cause. They are somewhat variable in size and seem to consist 

 of a thickening of the epidermis which becomes slightly raised, shining, 

 and brick-red in color. No attempt has been made as yet to deter- 

 mine whether they are present in the maggot before it leaves the 

 body of its host, but little doubt is felt that they will be found when 

 such examination is made. 



That these spots are directly or indirectly responsible for the failure 

 of the maggot to pupate is well indicated by the study of the numerous 

 half-formed puparia which result from the attempt on the part of the 

 larva of the parasite to do so. These are all more or less larviform, 

 but occasionally one is found one end of which is smooth and rounded 

 exactly as though pupation had successfully resulted, while the other 

 is shrunken and withered, resembling a dead larva. Careful exami- 

 nation revealed that in such specimens the reddish spots were absent 

 from the perfect portion and present in the withered. 



SUMMARY OF REARING WORK IN 1910. 



The accompanying tabulated results (Table VI) of an extensive 

 series of rearing experiments for the purpose of determining the 

 progress of the imported parasites of the brown-t^il moth also indi- 

 cate the extent to which that host is attacked by native parasites. 



