. The American entomologist. Entomology. ig2 THE AMERICAN ENTOMOLOGIST. was so great as to grind to pieces the mature forms when they came free, so it was with great difficulty I secured three specimens for identification. I doubt if their eggs have ever been seen before. " The eggs of the Simulia or Sand-fiy appear to be at present unknown; there is, however, little doubt that, like those of other gnats, they are deposited on the surface of the water, and in that situ- ation are hatched by the warmth of the sun, combined with the moisture of the ; {Newman, Hist, of Insects.) [
. The American entomologist. Entomology. ig2 THE AMERICAN ENTOMOLOGIST. was so great as to grind to pieces the mature forms when they came free, so it was with great difficulty I secured three specimens for identification. I doubt if their eggs have ever been seen before. " The eggs of the Simulia or Sand-fiy appear to be at present unknown; there is, however, little doubt that, like those of other gnats, they are deposited on the surface of the water, and in that situ- ation are hatched by the warmth of the sun, combined with the moisture of the ; {Newman, Hist, of Insects.) [Fig. 103.]. Eggs uf Simulium: apportion of mass from side; /', do. from top J c, d^ single eggs—enlarged (after Barnard). The eggs are long-ovoid in form, measur- ing X ;"". They are united in a compact layer, often with the sides so pressed together as to make the form some- what polyhedral, and generally with one end a little flattened or concave. When the fresh egg has imbibed glycerine, a large, somewhat irregular spheroid nucleus, with its distinct spherical nucleolus, ap- pears at one end. The embryonic devel- opment proceeds as usual with other flies. The young larva is larger at the anal end, which is the last to be withdrawn from the egg-membrane. Its terminal aperture serves as a sucker to attach by, and has its thick margin covered by rows of minute elevated points. Adjacent to this, the youngest larva bears some transparent cylindriform appendages, at least three in number, which are soon to disappear. In front of the anal segment is a ventral prominence. Its convex surface can be retracted to form a concavity or vacuum which helps the larva to cling fast and is essentially a quasi-sucking-disk. The pro- thorax bears a single proleg, nearly as long as the head, with its distal end covered by a great number of minute denticles or hook- lets. This and the anal area are the two points on which the maggot walks,somewhat as loopers or measuring-
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Keywords: ., bookcentury1800, bookdecade1880, booksubjectentomology, bookyear1
