THE TRICHOGRAMMA EGU-PARASlTE OF ALETlA. 



103 



according to Mr. Hubbard it is very abundant in Florida. Tho obser- 

 vations of the latter are interesting and well illustrate the importance 

 of the species. He found that this little egg-parasite, unaided and 

 alone, almost completely annihilated the fifth brood. At the beginning 

 of the fourth brood less than half the eggs of Aletia were destroyed. 

 July 27, when the eggs of 'this brood had nearly all been deposited, 

 about 75 per cent, were found to have been parasitized, the proportion in 

 some parts of the field reaching 90 per cent. About the middle of Au- 

 gust, while the eggs of the fifth brood were being laid, the proportion 

 destroyed by the Trichogramma exceeded 90 per cent, in all parts of 

 the fields, while, at the brood centers, careful estimates showed that but 

 three or four eggs out of a hundred escaped. He gives the following 

 account of the eggs of the species : 



" The mother works chiefly by day, depositing two ova in each egg of 

 Aletia or Heliothis. The eggs of the parasite hntch in forty-eight hours, 

 while that of their host darkens, and in a few days turns almost black. 

 On the seventh day after being stung it is vacated by the i)arasites, 

 which issue through an irregular hole gnawed in the side, each making its 

 own opening. Frequently after the inclosed parasites have formed their 

 pupa the shell of the Aletia egg shrinks about them, leaving two little 

 oval cells indicating the positions of the parasites within. A day or 



Fig. 32. — Apan'eleft aletice : a. female fly ; b, outline of head of larva in position to show the chitinized 

 parts of the luoui li, the mandibles not-visible, being wiihlrawii ; c, nuh of its mandibles as seen withm 

 the head of a mounted specimen ; d, cucoou ; c, jomD of antenna— all enlarged : nut. size of a and d in 

 hair-line (after Kiley). 



two before they issue the ruby-colored pupai of the parasites can be 

 plainly distinguished throuj^h the translucent shell of the destroyed 

 egg. I have invariably obtained two Chalcids from each, discolored 

 egg of Aletia or Heliothis collected." 



