( exiey ) 
having subsequently emerged from three of these pups within a few weeks, 
the others remaining in statu quo. Hence the question arises, how the 
parent Chalcis obtained access to the Sarcophaya larve for the purpose of 
depositing her eggs? It might be supposed that this opportunity was 
afforded at the time when the adult larva quits the body of the locust to 
undergo its final metamorphoses in the earth. But such would not have 
been the case in this instance, when the transition took place within a closed 
box remote from their accustomed haunts. The egg must therefore have 
been deposited at an antecedent period, either while the larva was within 
the body of the locust, or probably still earlier when the newly-hatched larva 
was about to penetrate into the body of the locust, as described by Professor 
Riley (loc. cit.), who also expresses his belief that the increase of and 
annoyance from natural enemies, in excessive abundance, ‘often prove a 
valid cause of migration” (l.c., p. 250). ‘The Tachina flies especially” (he 
adds) ‘‘ have been known to follow the locusts in dense clouds, and we have 
seen them so thick that not a locust could rise from the ground without 
being pursued by several; and there is no escape from their pursuit until 
the persecuted victim gets high in the air.” 
The following details from Mr. Calvert respecting the Sarcophaga 
lineata form an interesting sequel to his previous communications on the 
beneficial influences of the Callostoma in counteracting locust ravages :— 
‘ Dardanelles, July 14, 1881. 
“T beg to call your particular attention to the larva that is found in the 
body of the locust—no longer a matter of doubt. Each locust has from 
one to three of these larvae, which are seen on tearing open the neck and 
thorax. When the locust dies the larva, which is very active, leaves the 
body, and buries itself in the ground with haste—proved by experiments 
I have made. The head is provided with a couple of black hooks which can 
be drawn in; these hooks are used when the larva is in motion, and to bury 
itself. After a few hours the larva loses its liveliness in the ground. I have 
no pods at present to try if the larva feeds on the eggs of the locust. 
«A remarkable coincidence with the appearance of the parasite is the 
melting away of the immense swarms of locusts that were hatched: it is 
true some were devoured, but the great masses have died before the deposit 
of the egg; the country so freed round us is about twenty miles by forty. 
Tt is difficult to find locusts for specimens! The insects were very sickly 
this year. The locusts free from the body-parasite larva form the 
exception. How the parent introduces its egg in the locust has escaped 
my observation.” 
“ Dardanelles, July 21, 1881. 
‘Since I wrote on the 14th, on examining the larve I had put by 
I found these had changed to the pupa state, showing that they cannot be 
