OF WASHINGTON, VOLUME XIII, 1011. 173 



Dr. Lutz thinks that the females of all the species observed 

 by him suck blood and that they require this food for the de- 

 velopment of the eggs. He finds, however, that the different 

 species behave very differently in this respect, some showing a 

 preference for man, others for horses or other animals. Dr. 

 Lutz found that only one species is at all troublesome to man 

 and on this account he identifies it with the otherwise un- 

 recognizably described SiniK/iiini pcrtinax of Kollar. Co- 

 quillett pronounced this form identical with the North Amer- 

 ican Simulium vcnustum of Say; Lutz tentatively accepted 

 this synonymy, but rejected it in the second paper. This form 

 is found in great abundance throughout the coast ranges of 

 the states of Rio de Janeiro and Sao Paulo. Lutz states that 

 in behavior it resembles somewhat the yellow- fever mosquito 

 (Acdes ccilopits), being at the same time aggressive and wary. 

 It constantly hovers about a person, but only attacks in un- 

 guarded moments, so that by many the fly and the bite are 

 not associated, particularly as the resulting irritation does not 

 become apparent at once. As already stated, other species 

 show a distinct preference for animals other than man. Thus 

 what he calls alternately Simulium albimanum and S. 

 nigrimanum will hardly attack man in the presence of horses. 

 In attacking these it mostly selects the orbital margins of the 

 eyes, where the sucking females often form a complete ring. 



A remarkable circumstance noted by Dr. Lutz is that cer- 

 tain species behave differently in different localities or at dif- 

 ferent altitudes. Along the railway between Santos and Sao 

 Paulo, when the train stops at the stations at the foot of the 

 slope, SijuuUnm pcrtinax regularly enters the cars and attacks 

 the passengers. It shows a marked preference for very small 

 children, as becomes apparent by the crying of these, often 

 inexplicable to their parents. However, at the city of Sao 

 Paulo, lying at an altitude of 700 to 800 meters, Dr. Lutz 

 found that what he considered to be this same species does not 

 show the least tendency to attack man, even in close proxim- 

 ity to its breeding-places. Dr. Lutz does not think that this 

 difference in behavior is due to difference in altitude or tem- 

 perature and he points out that he has found Simulium ruhri- 

 thorax and S. montanum still attacking man at the height of 

 1,500 meters. Likewise Simulinm peril arum, which is com- 

 mon in Sao Paulo, there ignores man altogether, while Dr. 

 Lutz has received blood-filled specimens from a remote locality. 

 Lutz seeks to account for these differences in habits, which he 

 claims to have observed also in certain mosquitoes, in that 



