8 STEWART MACDOUGALL—-ON THE LIFE-HISTORY 
show all stages from still healthy not yet attacked ones to others 
beginning to brown and to others more than half brown, up to 
the perfectly withered and blotched pseudo-bulb which gives to 
the slightest pressure. 
The full-fed larva makes a cocoon by weaving together the 
fibres of the hollowed pseudo-bulb. The larve do not immedi- 
ately pupate on the formation of the cocoon, but lie as larvee on 
it may be for a lengthened period. One such larva, watched 
through a little chink cut in the cocoon, lay for twenty-three days 
before pupating, but others lay very much longer. In one 
experiment where the plant was Odondoglossum citrosmum, the 
larva had made its cocoon by December 17th, 1897, and the 
imago did not issue till April 24th, 1898. I did not wish to 
disturb this cocoon, and therefore cannot add the date of the 
change to the pupal condition. 
Once the larva becomes a pupa, the pupal stage lasts on an 
average twenty-four or twenty-five days. Here is a Table 
showing some of the times, where the changes were watched 
through a chink purposely made in the cocoon :— 
Pupa. Beetle issued. 
October 11, . : . November 4. 
January 27, . : . February 26. 
February 6, . : . March -? 
The escaping imago bites a little round hole in the cocoon and 
walks out, or, if the pseudo-bulb be unbroken, through pseudo- 
bulb as well. 
Development from egg to imago can take place in three and 
a half to four months, but may take much longer. Thus, in a~ 
Coelogyne cristata the beetles had an opportunity of egg-laying 
from June roth to July 27th, and I had issue of imagos on 
October 11th, October 18th, and the beginning of November. 
If a long time be spent in the cocoon before the larva pupates 
the above developmental period will correspondingly be 
lengthenend out; the character of the food and the temperature 
will also each have an effect. : 
