152 Psyche [October 



5. Tetrastichns {sens, laf) sp.. Family Eulophidse. 



A female of this undetermined species issued in Box No. 1 April 

 13. Others issued in small numbers thereafter till April 29, on 

 which date about a hundred, mostly males, were found in the tube 

 which had been left undisturbed for four days. They continued to 

 issue in considerable numbers till June 2. In Box No. 2, the first 

 individual appeared June 26 and the last July 7, and in Boxes Nos. 

 3 and 4 the periods of emergence were about the same. In Box 

 No. 5, about eighty issued from the thirty egg-masses between 

 August 2 and August 16. 



Quite a large proportion of the parasites failed to find their way 

 into the tubes. In Box No. 4 in particular about five hundred 

 were found in the debris after living insects had ceased to emerge. 

 It may very well be that some fault in the arrangement of the boxes 

 prevented individuals of all the species from emerging, and made 

 the records lower than they would otherwise have been. 



No. 5 was the only species to appear in any of the tubes con- 

 taining the isolated egg-masses. The percentage of parasitism 

 varies from 1 to about 12 per cent., showing that the number taken 

 was too small to justify any definite conclusions, although the 

 average percentage is not far from that of Box No. 4 in which the 

 dead insects were counted. Most of the egg-masses would seem 

 to be attacked, but only a few eggs seem to be parasitized in any 

 one egg-mass. 



In spite of the comparative abundance of this species no details 

 of its life-history could be ascertained, except that it passes the 

 winter as a full-grown larva in the host egg, and emerges in June, 

 a few days before the adults of Malacosoma. This failure was due 

 to the fact that the insect could not be induced to oviposit in the 

 eggs of its host. On one occasion a moth was secured in the act of 

 laying, and a parasite placed on the egg-mass; but the latter did 

 not oviposit, though it carefully explored the eggs. Finally, the 

 parasites were attracted to the eggs by dipping the latter in syrup, 

 but, as was to be expected, this did not overcome their unwilling- 

 ness to oviposit. It cannot be stated with absolute certainty 

 that they never did so, as eggs were sometimes left in the tubes 

 while the parasites were not watched. However, observations 

 lasting more than an hour, during which parasites were continually 

 walking about on the eggs, failed to demonstrate any egg-laying 



