EUPLECTRUS PARASITE OF ALEXIA. 105 



of tbe latter by means of a siugle thread. After crawling to a distance 

 of about half an inch it fastens this thread to the surface of the leaf, 

 and begins its cocoon. The body of the caterpillar is dislodged in time, 

 and frills from the leaf, but usually remains suspended by the connect- 

 ing thread. As the parasitic grub within its body increases in size, the 

 young caterpillar weakens and often falls to the ground, in w^hich case 

 the parasite climbs the nearest blade of grass and there makes its co- 

 coon." 



In escaping, the fly makes a lid-covered opening in the cocoon, as do 

 the other members of the genus. Mr. Schwarz is of the opinion that 

 this parasite does not always kill the worm, as upon several occasions 

 he raised to the perfect state worms which were scarred upon the pos- 

 terior end of the body, just as if one of these parasites had emerged. 

 Two secondary parasites have been bred from the Apanteles — the one 

 a Chalcid^^ and the other an Ichneumonid belonging to the genus 

 Hemiteles. 



CoMSTocK's EUPLECTRUS.— Professor Comstock, in the Eeport on Cotton 

 Insects, 1879, figured and quoted passages from his notes concerning 

 a parasite of the Cotton Worm, which he called "the unnamed Chalcid." 

 In the August (1880) number of the Canadian UntomoJogist the species 

 was described by Mr. Howard as Euplectrus comstocldi. This description 

 he has somewhat revised, and it will be found in the notes.^^ During 

 1880 this parasite was studied by us and by different agents of the Com- 

 mission in Alabama and Florida, and in the January (1881) number of 

 the American Naturalist Mr. Schwarz gave a very full account of its 

 life history. From this article we take the following facts : 



The egg of the paj-asite is elongate oval, strongly convex above and 

 somewhat flattened beneath; no sculpture is visible under an ordinary 

 lens. Its color is uniformly brown, 

 and almost black just before 

 hatching. The number of eggs 

 laid by the female Euplectrus on 



a single Cotton Worm varies from ^^^ 33.-Aletia larva infested by larv^ of JEuplec- 



one to fifteen, the most common trus comstocku. (Original.) 

 numbers being three, five, and seven. They are always laid in a group, 

 the individual eggs sufficiently separate from each other to allow room 

 for the development of the larvae. It seems altogether probable that the 

 time required for the development of the eggs does not exceed two days. 

 ThiB Cotton Worms attacked by these parasites are usually less than 

 one-third grown, but not less than one day old. The eggs of the para- 

 site are laid on the middle of the back of the worm, sometimes a little 

 to one side or the other, and upon one occasion they were seen fastened 

 just above one of the middle pair of thoracic legs. 



The delicate egg-shell splits longitudinally and discloses the white 

 larva, which gradually works the shell down the sides of its body until, 

 in less than twelve hours, it disappears below the rapidly-growing para- 



