307 



of which seemed to cross the river or ti) goto cattle staudiug in the 

 middle of the stream. The cattle on clear days came to the river 

 about o'clock in the morning, and remained standing in the middle of 

 the river until a o'clock in the afternoon, when they went to grazing, to 

 return at 9 o'clock the following morning. Most of the cattle stood on 

 tlat rocks j^rotruding out of the water, so that no part of their body or 

 legs were submerged; but in si)iteof this fact, while they were standing 

 in the river they were unmolested. The actual oviposition of these 

 insects, which are found to occur in such extraordinary numbers, was 

 witnessed on March 1 and the two or three following days. An old and 

 feeble animal, which had laid down and had not strength to rise, was 

 observed to be attacked daring this time by about 50 flies, of which 

 upward of a dozen were captured. The flies were observed to approach 



Fig. 44.— Htpoderma lineata: a, eggs attached to hair; b, c, d, dorsal, ventral, an d lateral view of 

 egg; e. embryonic or lirst larva, as seen in egg; /. g, mouth-parts of same enlarged; h, anal segments 

 of same still more enlarged (original). 



very swiftly and deposit their eggs anywhere on the sides, belly, or 

 tail, near the anus, and on the front legs. The flies were left unmolested 

 in many cases until, after remaining on or about the animal from five 

 to ten minutes, they flew off. The eggs were then found without <lif- 

 flculty, usually placed four to six together, and listened to the hair. 

 Flies were also captured and eggs were deposited in confinement. A 

 large number of the flies and eggs, both dried and in alcohol, were sent 

 to me. The structure of the lower portion of the egg, which has been 

 more or less correctly shown in some of the earlier illustrations, is well 

 adapted for clasping a hair. It consists of two lobes, forming a bulb- 

 ous enlargement, which is attached to the egg by a broad but rather 

 thin neck, so that when the latter is viewed sidewise it appears as a 

 slender pedicel. (See Fig. 44 a, d.) 



