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Show 286 INSECTA. in the lumps or tumours formed on the skin, others in some part of the interior of the head, and the rest in the stomach of the animal destined to support them. The eggs that produce the first are deposited by the mother under the skin by means of a squamous ovipositor composed of four tubes fitting one within the other, armed at the end with three hooks and two other appendages. This instrument is formed by the last annuli of the abdomen. These larvre called taons by the farmers are not compelled to change their domicil, finding themselves when hatched in the midst of the purulent matter on which they feed. The ova of the others are simply deposited and glued to various parts of the skin, either in the vicinity of the natural cavities into which the larvre are to penetrate and take up their abode, or on those spots which the animal is in the habit of licking, in order that the larvre may be transported on its tongue into its mouth, where they can proceed to their destined dwelling. Thus the female lEst1·us ovis places her eggs on the internal margin of the nostrils of the Sheep, which is no sooner aware . of it, than it becomes agitated, strikes the earth with its feet and flies, with its head to the ground. The larva insinuates itself into the maxillary and frontal sinuses, and clings to their lining membrane by means of the two stout hooks with which its mouth is armed. It is thus also that the (Estrus equi deposits her eggs at intervals, without alighting and by balancing her body in the air, on the inner side of the legs of the Horse, on the side of the shoulders, and rarely on the withers. The fE. hcemor1'hoidalis, whose larvre also inhabit the stomach of the same animal, places her eggs on his lips. The larvre cling to his tongue, and descend through the esophagus into the stomach where they feed on the humour secreted by its lining membrane. They are usually found round the pylorus, and rarely in the intestines. They are frequently suspended there, in clusters, in great numbers. M. Clark however is of opinion, that they are rather useful to the animal than injurious. The larvre of the CEstri are usually conical and destitute of feet. Their body, exclusive of the mouth, is composed of eleven annuli, covered with little tubercles and small spines, frequently arranged like cords, that facilitate its progression. The principal organs of respiration are situated on a squamous plane of the posterior extremity of body, which is the largest. It appears that their number and disposition are different in the gastric larvre. It also seems that the mouth of the cutaneous larvre is only composed of mammillre, whilst that of the internal ones is always armed with two stout hooks. Both kinds, having acquired their growth, leave their abode and DIPTEH.A. 287 fall to the ground ' m· w h't ch they conceal th . become pupre under their own sk' l'k emselves, m order to Th . . m, 1 e other Dipt f . f . ose, whtch mhabit the stoma h ./! 11 era o thts amlly. d · c IO ow the track f h · . an a1ded perhaps by the frocal d' h 0 t e mtestmes, \A.. 1sc arge of th · 1 anum. These metamorphoses us II . e amma ' escape per M d H ua y occur m June d J I . e umboldt met witll IndI' ans 1.1 1 S outh A · an u y. . men was covered with little tu merlca, whose abdo-the larvre of an CEstrus M r mours, pt·oduced, as he presumed, by · o e recent obs · t' rate this opinion. They pe h b I erva Ions seem to corrobo-r aps e ong to s · genus CuTEREBRA of M • Cl ar k wh ose 1a rv r orne species of the certain Mammalia. ' re Ive under the skin of It would also appear that larvre 1 have been withdrawn from th '~na ogous to those of an (Estrus, but these observations have e maxillary o.r frontal sinuses of Man; (E b . D not been sufficiently prosecuted(!) · ov~s, e Geer; Clarck. Lin T ... · six to seven lines · 1 ' • rans., III, xm, I, 6. From with a black band·mbdength, an~ densely pilose; thorax yellow, ' a omet1 white at ba · 1 f mity; wings somewhat b se, Wit l a ulvous extre- T o scure. and ~eo~~al~ deposits her eggs under the hide of healthy Oxen ' o not more than two or three years of age. The (1~ In the second edition of the Nouv. Diet d' . . pubhshed a new systemat' • Htst. Nat., article CEstre, I have Some h . .tc arrangement of these Insects. ave a very dtstmct and retractile b . M. Clarck and the C pro oscts: the genus CuTEREBRA. of ' EPUENEMYIA Lat I th fi plumous, and the palpi are not ' . n e rst, the seta of the antenn~ is I · apparent. The CEstrus b t· f · . ongs to thts genus . M · Cl arck h as d escr.t bed th ucc·a us o Fabrtcms be- I have published a third the epJ. . . h ano er speCies, the cuniculi, and the antenn~ is simple i~ th Cnprzum; t . ey are all from America. The seta of CEstrus trompe, Fab. is the ;ypeepfletlnemytre, and the palpi are apparent. The Th ' o 1e genus. e others are destitute of a proboscis: the seta o . pie. Two palpi are still visible in th f the antenna: IS always simCEst. tarandi. e ffiDEMA.GENA., a genus established on the ~~~e three following genera they disappear. . Hypoderma:-H:rPODERMA.-have a s II . . ts the character of the rr:r t b . ma oval sltt m the form of a Y. Such t u:-s rus om. The Ceph 1 . wo very small, punctiform tub . . a _emyJ~-CEPHA.LEM:UA.-have are distant, and the alul~ covere:~~e~~~h~ch a~vestJge~ of the pal pi. The wings -these two tu»ercles also exist but th ele~- strus oms. In the ffistri-ffisTRus and the alula: on1y cover a p t~ f e wmgs are Cl'Ossed on their inner margin th or 10n o the halteres (E t · ' o ers. M. Meigen calls this last ~ _s rus equt, Fab., and some Leach. AU the others ac d' genus Gastrtea; tt ts the Gasterophilus of Dr Here, the posterior c;lls ~~.: ~~g t~teese g~ntlcmen, form the single genus CEstru3. posterior margin. in G t lose y transverse nervures, before they reach the h ' as rus, t ley are clo d b th . t ese and some other characters in th N se ~ at m.argm. We have described e ouv. Dtct. d'Htst. Nat., article CEsfre. |
