Life History of certain Little-known Aphidirhr. 213 



number of young. In the mean while the ground has probably 

 been plowed, and some crop sowed. In case this crop is corn 

 the ants transfer the lice to the corn roots; but if it is oats or 

 wheat they may continue to rear the lice on Setaria and Polyg- 

 onum. The young from these stem-mothers become adult in 

 about a fortnight, and some of them are apterous and others 

 winged. The winged specimens fly to other hills either in the 

 same or neighboring fields, where the ants are waiting to receive 

 them and proceed to establish colonies. Whether in ground 

 not planted to corn more of this second generation become 

 winged than where corn is present, or not, I cannot say; nor do 

 we know how long the lice can continue to develop on Setaria 

 and Polygonum. This second generation bring forth vivipa- 

 rous young (mostl}" wingless); and generations of viviparous 

 females continue to develop on corn roots throughout the 

 summer. In autumn the true sexes are produced (both being 

 apterous), and the eggs are deposited by the oviparous females 

 in the mines of the ant colonies. These eggs are cared for by 

 the ants through the winter, and the young lice that hatch 

 from them in spring are provided for as described above. 



Description. 



Wingless male. — Body 1.4 mm. long; 7 mm. wide. An- 

 tennae .9 mm. long; cornicles, .08 mm. long; cauda .05 mm. long. 



Body flattened; sides nearly parallel between middle coxap 

 and cornicles; behind cornicles tapering rapidly to cauda: nar- 

 rowing in front of middle legs. Greenish black with a glaucous 

 bloom; head above black; dorsum of prothorax with a narrow 

 black transverse band; dorsum of mesothorax with a similar 

 wider band, dorsum of metathorax with a narrow band not ex- 

 tending to the margins, — all indistinct and in some lights not 

 distinguishable. Eyes black; antennas, legs, and cornicles 

 blackish. Caudal segments of abdomen with indistinct trans- 

 verse dark bands. Ventral surface of thorax blackish, of abdo- 

 men dark green with black patch at caudal extremity. Cauda 

 hirsute. Margins of abdomen wavy. Legs long, hairy. An- 

 tennas robust; joint I swollen; II about equal to I in length, 

 but smaller; III longer than I and II; IV and V subequal, IV 

 slightly longer; VI slightly longer than V, and VII about 



