. Animal parasites and human disease. Insects as carriers of disease; Medical parasitology. BLACKFLIES 481 seen in Fig. 223. The breathing filaments vary greatly in dif- ferent species and may have from four to GO Ijranches. The adults escape from the pupae after from one to three weeks through a slit in the back, and are carried safely to the surface by a bubble of air which has been collecting inside the old pupal skin. The adults are short lived and lay their eggs soon after emergence. The whole life of a gen- eration from egg to egg may be passed in from six weeks to two months or more. So
. Animal parasites and human disease. Insects as carriers of disease; Medical parasitology. BLACKFLIES 481 seen in Fig. 223. The breathing filaments vary greatly in dif- ferent species and may have from four to GO Ijranches. The adults escape from the pupae after from one to three weeks through a slit in the back, and are carried safely to the surface by a bubble of air which has been collecting inside the old pupal skin. The adults are short lived and lay their eggs soon after emergence. The whole life of a gen- eration from egg to egg may be passed in from six weeks to two months or more. Some spe- cies have several generations a year but the majority produce but a single brood a year. The Canadian species already referred to is seen only for a few weeks in May and early June, during which time it is locally exces- sively abundant. Most species are diurnal, but the author found the Ontario species to be most active from late afternoon until dark, and again early in the morning. This species will also bite readily at night in the presence of artificial light. The species of blackflies are numerous, but are all included in the single genus Simulium, with several subgenera which some workers elevate to the rank of true genera. Some species do not attack man but viciously attack various domestic animals. While on a collect- ing trip in the Cascade Mountains of Oregon (-^^ter Jobbins-Pom- the author found it necessary to keep the pack animal picketed in the smoke of the camp fire constantly to pro- tect the poor creature from the blackflies which congregated in large numbers about his eyes and nose, yet neither the author nor his companion was ever bitten by one of these flies. One of the most troublesome species in the United States is S. pecuarum, the famous buffalo gnat of the south central portion of the country. This species was formerly more abundant than now, and was a terrible scourge to mules and cattle. S. venustum is one of the most important molesters of ma
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Keywords: ., bookcentury1900, bookdecade1910, booksubjectmedical, bookyear1918
