WEBVTT Kind: captions; Language: en 00:00:00.000 --> 00:00:01.001 [...] 00:00:04.000 --> 00:00:09.001 [...] 00:00:24.001 --> 00:00:29.001 [...] 00:00:38.000 --> 00:00:38.001 [...] 00:00:33.001 --> 00:00:39.001 Of 00:00:39.001 --> 00:00:46.000 all the blood sucking insect pests which played mankind the 00:00:46.000 --> 00:00:48.000 mosquitoes among the most pernicious. 00:00:49.000 --> 00:00:51.001 Mosquitoes are divided into two great tribes. 00:00:52.001 --> 00:00:58.000 The anopheles some of which transmit malaria assume this position in biting. 00:00:58.001 --> 00:01:04.001 And the cure the things which may spread yellow fever dengue and filler I. 00:01:04.001 --> 00:01:04.001 [...] 00:01:04.001 --> 00:01:06.001 Is this right in this position. 00:01:09.000 --> 00:01:11.000 The mosquito body is divided into three parts. 00:01:12.000 --> 00:01:12.001 The head. 00:01:13.001 --> 00:01:14.000 Thorax. 00:01:15.000 --> 00:01:15.000 And abdomen. 00:01:16.000 --> 00:01:20.000 The thorax bears three pairs of legs and a single pair of wings. 00:01:21.000 --> 00:01:27.000 The head bears the eyes the feelers around teni the paltry and the beat. 00:01:28.000 --> 00:01:32.001 The abdomen bears no special structures except the reproductive organs. 00:01:33.001 --> 00:01:37.001 In the female the antennae are fringed with short hair rising 00:01:37.001 --> 00:01:39.000 from the edge of each segment. 00:01:39.001 --> 00:01:40.001 While in the mail. 00:01:42.000 --> 00:01:45.001 The antennae are conspicuously tufted with large worlds of hair. 00:01:46.001 --> 00:01:50.001 The prominent antennae are the chief distinguishing features of the mail. 00:01:51.000 --> 00:01:54.000 A mosquito bites primarily to obtain food. 00:01:54.001 --> 00:01:58.001 As the female settles down to a blood meal her beak 00:01:58.001 --> 00:02:00.000 appears to bend at the middle. 00:02:00.001 --> 00:02:05.000 Actually the beak consists of a jointed protective sheath that bends. 00:02:06.000 --> 00:02:09.001 While a thin lancet enclosed within the sheath pierces the skin. 00:02:10.001 --> 00:02:14.001 A cross section of the beak shows that this lancet consists of 00:02:14.001 --> 00:02:16.001 six separate stylus. 00:02:17.000 --> 00:02:22.001 Which in close between them two tubes one for saliva and one for blood. 00:02:28.000 --> 00:02:33.000 A small amount of the insect saliva is injected into the wound to prevent 00:02:33.000 --> 00:02:36.000 clotting of the blood which is then sucked up as food. 00:02:37.000 --> 00:02:41.000 The abdomen swells perceptibly as the blood meal progresses. 00:03:00.001 --> 00:03:04.000 A male mosquito cannot bite or suck blood. 00:03:05.000 --> 00:03:09.000 A newly emerged male may try blood suction without success. 00:03:10.000 --> 00:03:14.001 The beak of the male is not constructed to pierce human or animal skin. 00:03:16.000 --> 00:03:19.000 Male mosquitoes feed exclusively on vegetable juices. 00:03:20.000 --> 00:03:21.000 The nectar of flowers. 00:03:21.001 --> 00:03:23.000 The juice of fruits. 00:03:24.000 --> 00:03:28.000 The female also feeds on vegetable juices but blood forms 00:03:28.000 --> 00:03:29.001 the major part of her diet. 00:03:32.001 --> 00:03:35.000 Some mosquitoes lay eggs on the surface of water. 00:03:36.000 --> 00:03:37.000 Some near the water. 00:03:37.001 --> 00:03:39.001 Some mosquitoes like shaded water. 00:03:40.001 --> 00:03:41.000 Others some lit. 00:03:42.001 --> 00:03:44.000 Some require fresh water. 00:03:45.000 --> 00:03:46.000 Others prefer salt. 00:03:47.000 --> 00:03:50.000 But all mosquitoes require water of some kind. 00:03:51.000 --> 00:03:57.001 Flood water mosquitoes lay their eggs singly in mud near water or in other areas 00:03:57.001 --> 00:03:59.000 which later may be covered with water. 00:04:00.000 --> 00:04:06.000 The eggs of flood water mosquitoes can remain dormant sometimes for years until 00:04:06.000 --> 00:04:10.000 the conditions of warmth and water are suitable for hatching. 00:04:11.000 --> 00:04:14.000 Flood water mosquitoes living in regions having cold winters 00:04:14.000 --> 00:04:16.001 overwinter in the egg stage. 00:04:21.001 --> 00:04:27.000 A section of frozen mud taken from a swamp where flood water mosquitoes are known 00:04:27.000 --> 00:04:33.000 to breed in summer when immersed in water at room temperature will cause mosquito 00:04:33.000 --> 00:04:35.001 larvae to appear a few days later. 00:04:37.000 --> 00:04:40.001 Most other mosquitoes overwinter in the adult stage. 00:04:41.001 --> 00:04:47.000 Such hibernating adults can be found in hollow trees, in culverts, 00:04:49.000 --> 00:04:54.000 under houses, porches or in cellars. 00:04:55.000 --> 00:05:00.001 These mosquitoes lay eggs fitted with two floats on the surface of the water or 00:05:00.001 --> 00:05:04.000 in large buoyant masses called egg boats. 00:05:04.001 --> 00:05:10.001 Except when overwintering, mosquito eggs hatch into larvae soon after they are 00:05:10.001 --> 00:05:13.000 laid, sometimes in less than a day. 00:05:14.000 --> 00:05:18.001 The mosquito larvae after hatching is usually whitish or gray in color. 00:05:19.000 --> 00:05:23.001 Floating at the surface of the water, it inhales air through its breathing tube. 00:05:26.000 --> 00:05:32.001 It soon moans, shedding the original larval skin, emerging somewhat larger into 00:05:32.001 --> 00:05:35.001 the second instar or period of larval development. 00:05:39.000 --> 00:05:44.000 In the same way, the larva passes through the third 00:05:44.000 --> 00:05:48.001 and into the fourth 00:05:48.001 --> 00:05:51.000 and last instar. 00:05:52.000 --> 00:05:57.001 The larva has no legs or other organs of locomotion and moves by a series 00:05:57.001 --> 00:05:59.000 of jerks or wiggles. 00:06:00.000 --> 00:06:03.000 In some species, the body of the larva is transparent 00:06:03.000 --> 00:06:05.001 and the heart action may be observed. 00:06:06.001 --> 00:06:12.000 As in all insects, the contraction waves begin posteriorly at 00:06:12.000 --> 00:06:14.000 advanced anteriorly. 00:06:14.001 --> 00:06:17.001 Watch closely this tail-to-head pulsation. 00:06:25.001 --> 00:06:31.001 The head and thoracic segments of the larva are enlarged, sometimes twice as 00:06:31.001 --> 00:06:33.000 broad as the abdominal segments. 00:06:33.001 --> 00:06:38.001 The abdomen is divided into nine segments, the first seven of which resemble each 00:06:38.001 --> 00:06:40.001 other closely and differ little in species. 00:06:41.001 --> 00:06:46.001 On the ninth segment are the anal gills. On the eighth segment, tube 00:06:46.001 --> 00:06:48.000 through which the larva breathes. 00:06:49.000 --> 00:06:54.000 Most larvae hang head down with the breathing tubes at the surface of the water. 00:06:57.000 --> 00:06:59.001 The anophilus larva, however, lies horizontally 00:06:59.001 --> 00:07:01.000 when feeding at the water surface. 00:07:02.000 --> 00:07:06.000 Examined closely, the mouth parts are seen to be in constant motion. 00:07:10.001 --> 00:07:16.001 The anophilus larva, which can turn its head 180 degrees to facilitate feeding, 00:07:17.000 --> 00:07:22.000 sets up currents at the water surface with its mouth brushes to bring within 00:07:22.000 --> 00:07:24.001 range the floating particles on which it feeds. 00:07:29.000 --> 00:07:34.000 When the larva has reached the fourth instar, appendage buds, which will later 00:07:34.000 --> 00:07:39.000 grow into the legs and wings, can be seen on the ventral side of the thorax 00:07:39.000 --> 00:07:42.000 through the semi-transparent cuticle. 00:07:46.000 --> 00:07:53.000 In the second instar, these appendage 00:07:53.000 --> 00:07:58.000 buds, while already differentiated, are not yet well enough developed to be 00:07:58.000 --> 00:08:04.001 visible at this point of growth. Full grown, 00:08:05.000 --> 00:08:09.001 the larva now begins the change through the pupil form. Telescoping its body 00:08:09.001 --> 00:08:15.000 slightly, it commences to shed its cuticle, usually beginning at the head. 00:08:16.001 --> 00:08:20.001 For a while, the insect may rest, its new pupil head 00:08:20.001 --> 00:08:22.001 projecting from its larval body. 00:08:42.000 --> 00:08:48.000 Finally, with a few convulsive jerks, the larval cuticle, complete with breathing 00:08:48.000 --> 00:08:53.000 tube, is cast off, and the mosquito assumes a new 00:08:53.000 --> 00:08:56.000 guise, that of a pupa. 00:08:58.001 --> 00:09:05.000 In this stage, no food is taken, although the body remains in water. The pupa has 00:09:05.000 --> 00:09:11.000 its head and thorax punched into one mass, with no obvious organs except two 00:09:11.000 --> 00:09:17.001 black spots, which will later become eyes, and two horn-shaped appendages 00:09:17.001 --> 00:09:22.000 at the top of the thorax, which serve as breathing tubes. 00:09:24.001 --> 00:09:29.000 The abdomen terminates in two swimming paddles, which 00:09:29.000 --> 00:09:30.001 propel the pupa through the water. 00:09:31.001 --> 00:09:37.000 As the pupa grows older, the wing pads become recognizable. Holded up against the 00:09:37.000 --> 00:09:42.001 wing pads are the cases of the long, jointed legs of the adult. The pupil stage 00:09:42.001 --> 00:09:49.001 is short-lived, lasting usually only one to four days in warm weather. When the 00:09:49.001 --> 00:09:55.000 adult is fully developed within the pupil case, the pupa is less active. It tends 00:09:55.000 --> 00:09:58.001 to straighten out and takes on a shining, glittering appearance. 00:10:01.001 --> 00:10:04.000 Suddenly, the skin bursts along the middle of the back. 00:10:08.000 --> 00:10:14.001 The adult rises up almost vertically, literally oozing out of the pupil envelope. 00:10:35.000 --> 00:10:37.000 The wings are first freed. 00:10:42.001 --> 00:10:46.001 Finally, the long legs are carefully extended to support the 00:10:46.001 --> 00:10:48.000 fully developed body. 00:11:04.000 --> 00:11:09.001 In a few minutes, the drying process is complete. The insect 00:11:09.001 --> 00:11:11.000 is now ready to fly. 00:11:12.000 --> 00:11:17.001 With this final transformation, there has evolved the familiar adult mosquito. 00:11:18.001 --> 00:11:21.000 The mosquito is an excellent example of an insect 00:11:21.000 --> 00:11:23.001 undergoing complete metamorphosis. 00:11:24.000 --> 00:11:30.001 The egg, the larva, the pupa, and the adult. Truly, the female of the species 00:11:30.001 --> 00:11:33.000 is more deadly than the male.