214 



PARASITES OF GIPSY AND BROWN-TAIL MOTHS. 



Fig 



Blepharipa scutellata: 



Eggs in situ on fragment of 

 leaf. Enlarged. (Original.) 



Japanese Crossocosmia sericarise, which was the subject of the original 

 investigations by Dr. Sasaki through which this peculiar habit was 

 discovered. The full life of the fly from the deposition of the eggs to 

 the issuance of the adult, some 10 or 11 months later, has been the sub- 

 ject of a special series of investigations by Mr. W. R. Thompson, who, 

 it is expected, will shortly publish the results of his studies. 



It is worthy of note that the results of Dr. 

 Sasaki's observations have been abundantly 

 confirmed in very nearly every respect in which 

 there is not an actual difference between the 

 habits of Blepharipa and those of Crossocosmia. 

 Each female fly is capable of depositing sev- 

 eral thousands of eggs upon the foliage of trees 

 frequented by the caterpillars of the chosen 

 host, but it is not known to what extent she 

 employs discretionary powers in the selection 

 of these trees. Presumably she is attracted 

 to those upon which the host caterpillars are 

 most abundant. Whether one sort of tree is 

 more attractive to them than another is not 

 known. The young larvae hatching from the eggs which have 

 escaped maceration by the mandibles of the caterpillars pass through 

 the wall of the alimentary canal and immediately proceed to take 

 full advantage of the physiological changes brought about in the 

 host organism as the direct result of their presence. There are two 

 larval ecdyses and three larval stages (as is the case with every other 

 parasite of which the transfor- 

 mations are sufficiently well 

 known to make any statement 

 possible), and the manner of life 

 undergoes a change with each 

 ecdysis. 



The first-stage larva embeds 

 itself in the tissues of the host, 

 which apparently react in a man- 

 ner somewhat suggestive of the 

 reaction which results in the 

 growth of a vegetable gall fol- 

 lowing attack by a gall-making 

 insect. The drawings of these 



gall-like bodies containing the larvae (fig. 38), as well as the drawings 

 of the egg and of the second-stage larval "funnel" were prepared 

 under the direction of Mr. Thompson as illustrations for his forth- 

 coming paper. 



The second-stage larva undergoes a complete change in its manner 

 of life, and its activities result in the formation of a tracheal "funnel," 



Fig. 37.— a, Egg of Blepharipa scutellata, showing 

 characteristic sculpture and markings; b, egg of 

 Pales pavida. Greatly enlarged. (Original.) 



