286 Annals Entomological Society of America [Vol. IV, 



fact of their interbreeding with each other and with humeralis 

 was discovered, and then the work was directed along the line 

 of heredity investigation. About four hundred beetles were 

 reared to maturity from about three thousand eggs hatched. 

 These beetles proved much more difficult to rear than the 

 larger species such as Hippodamia convergens and Coccinella 

 qitinque-notata because of their more limited range of food and 

 more delicate constitutions. All large aphids brought disaster 

 in the breeding cage and sometimes even the small cottonwood 

 louse, Chaitophorus populicola Thos. was rejected. In the latter 

 case it was perhaps due to an odor left by a certain species of 

 attendant ants, since these lice did not always prove objection- 

 able. One feed of unfavorable lice would sometimes cause the 

 death of from one-half to nine-tenths of a cage of larvae. 



Work was begun with these beetles with the capture, 

 May 13, 1910, in the foothills near Fort Collins, Colorado, of 

 a pair of annectans. Eggs of this female were laid in the lab- 

 oratory and the larvae reared. When the beetles eight in 

 number emerged, four proved to be like the parents and four 

 were humeralis. Three subsequent batches of larvae giving 

 nine adults, were reared from eggs laid by this female and her 

 spotted daughters with the result that three of the beetles 

 were annectans and six were humeralis. 



For the purpose of obtaining more material and also of 

 ascertaining how frequently such mixing occurred, two or three 

 dozen pupae of this species were collected outdoors, and as soon 

 as the beetles emerged and the colors developed the different 

 forms were isolated in separate cages. About fifteen percent 

 were humeralis and the rest were about evenly divided between 

 melanoplcura and annectans. The humeralis beetles escaped 

 by accident, but from the eggs of the other forms a considerable 

 number of larvae were reared to maturity. From the eggs laid 

 in the melanopleura cage thirty beetles were reared, and in each 

 batch a large proportion were annectans, sometimes over half 

 the batch and once the entire batch. Practically the same 

 proportions were obtained from eggs of one or two females 

 captured at other times. Besides the forms already mentioned 

 three individuals of coloradensis appeared among the progeny 

 of the above mentioned cage. Unfortunately these were not 

 used for breeding purposes but were pinned up and put in the 

 collection. Breeding experiments are now, however, in prog- 

 ress with this form. 



