Pupa.- The delicacy of the chitinous covering of the early stages can be seen during the period of transformation. In Phloeothripidje there are usually three strong, raised spines near the base of the vein on the forewing.
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FemaleovfposUor.— The most distinct external sexual character of the female is the ovipositor, which is attached to the ventral side of the eighth and ninth abdominal segments (Plate XI, Fig. 121) and is. 110 PROCEEDINGS OF THE NATIONAL MUSEUM. vol.xxvi. . extremity below the abdomen of the female, so that the ventral surfaces of the posterior segments face each other.
DEFORMITIES
The copulatory apparatus of the male is pushed out, while the female ])ends the tube upwards so as to leave the sexual opening free. The bond lasts about half a minute, when the female begins to move and the male leaves her back, but the bond is not immediately broken and the stronger female pulls the clinging and struggling male behind her.
REPRODUCTION
The explanation for the relative lack or absence of males is found in another method of g-generation. It seems that parthenogenesis must take place to some extent in those species in which males are relatively rare or active only for a short season.
DISSEMINATION
The Tubulifera are very slow and deliberate in their movements, both in crawling and fl3dng, and the}^ never leap or run. When suddenly the upright parts arc }) thrown together and the insect thrown a considerable;.
DEVELOPMENT
The pads extend obliquely outward along the sides of the body and do not overlap each other. The development of the male apparatus occurs in a very similar way to that of the female ovary.
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ECONOMIC CONSIDERATIONS
Although many plants suffer from this. the destruction of their leaves seems to be the most serious to the onion. Grasses and grains can be included in a third class, where the nature of the damage differs slightly. It has already proven to be a serious pest that can completely destroy a crop and is extremely difficult to control.
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CHAKACTEES OF THYSANOPTERA
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MP^.TFIOD OF MEASUREMENTS
In the case of the comparative lengths of segments of the antenna\ all . measurements have been made with a |-inchol) objective and a 1-inch eyepiece. The number of the segment has been indicated above the line, and directly below the number of spaces on the eyepiece micrometer covering the segment.
INDIVIDUAL VARIATIONS
It has been shown that there are small individual variations in the length of corresponding segments in different samples of the same. species, and even in the two antennae of the same specimen, there is still .. a very close agreement in this respect, and the proportions hold very well. All statements of lengths, both actual and comparative, in the descriptions herein are based on actual measurements made in one or the other of these ways, being an average of the total number of specimens used in the description.
CHARACTERS OF TEREBRANTIA
The development of the forewings appears to be in inverse proportion to the development of the spine carried on. The median vein is without spines, such as e.g. carried on the veins in the forewing.
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UVitoutspinesathindanglesofprothorax lii(iji]iut]irlp>!(p. 160) q /With twolong spineateachhindangleofprothorax 10 iWith one long spineateachhindangle of prothorax Pi SYNOPSIS OF SPECIES Wings are almost always fully developed in females, about four-fifths as long as the torso and in the center about one-seventh as wide as long, sharply pointed at the tips, heavily fringed on both edges. Abdomen) wider than mesothorax, barely twice as long as wide (the segments usually overlap considerably, giving a dark and light brown checkered appearance); spines around the last two segments medium length and stout, dark brown and conspicuous; ovipositor of good length. 137 Abdomen elongate-oval in outline, bluntly pointed at the tip. one and abdomen oblong-ovate in outline, bluntly pointed towards the tip. one and four-tiftes times as lono-as l)pad; spine on last two segments short, weak and inconspicuous; ovipositor short and weak. The terminal segment of the al)domen in the female is slightly elongated and approaches a tubular shape, split open at the top; each side bears a short, extremely stout spine, and similar stout spines are borne on the sides of the eighth segment. End of abdomen bluntly rounded; the ninth segment bears a stout spine in the center of each side and a pair of similar spines are close together near the dorsal line above. 141 . protuberances whose inner edges are parallel and the black mark tapers to a point anteriorly; on each side of these peculiar protuberances stands a longitudinal, slender spine; about the middle of each side of the ninth segment is a very erect, angular, chitinous projection, shaded almost black, supporting on the inner side an extremely short, stout, dark brown, blunt spine; other spines on this segment slender but not very long. The tenth segment is blunt at the end and bears a series of short, small spines above, near the posterior margin; the nine is notched on the upper side about half as often, which at the tip does not (][uite extend to the tip of the nine or on the lower side; abdomen 3'^ yellow-brown. 143 (appearing as a band) extends along two-thirds of the width of (appears as a band) extends along two-thirds of the width of the dorsal plates of segments two through seven near their anterior ends;. Antenna eight-segmented, more than twice as long as head, bases separated by about two-thirds the width of a basal segment; the relative lengths of the segments:. J/rt/J.-Similar to female with the following exceptions: Length 0.64 mm.; chest width 0.19 mm.; abdomen only four-fifths as wide as thorax, and more than twice as long in length, nearly cylindrical in seventh segment; eight to ten conoids; spine on last short segment; large and orange-brown testicles. Eyes of medium size, together covering about half the width of the head, dark, slightly protruding; 100 ACTIVITIES OF THE NATIONAL MUSEUM. vol.xxv, yellowish; pronotum often extends considerably over fron1!| . edge of inguinal plate. Wings present, long, about one-sixteenth abroad as long; Forewings expanded at the base, with two longitudinal veins, the second l)rancher from the first not far from the base of the wing. Wings very broad and long, so that the}^ extend beyond the end of the abdomen. In Florida, Quaintance found the ^^g stage to last from three and a half to four days in summer; the larval stage of seven ton days, during which the larva molted twice; the nymph stage four days, the total life cycle thus requiring about sixteen days. Packard's description is unidentifiable, it is sufficient to show that the insect was not, nor is it, Thrips tritici Fitch. Remaining balance of OAnpositor. however, they tricked her into thinking that her specimens are all male, when thcA' are actually all female. It also seems probable that the so-called "stick" of the Tul-u-Lifeian female is but the vestige of a former ovary. Along the edges of each wing there develops (^ a long, slender fringe, which is single except near the tip of the trailing edge of the forewing, where it is double for a short distance. The last segment is simply a])otlisexesand that its base , below One finds the characteristic sexual characteristics, visible by a short, strongly chitinized rod on the ninth segment near the base of the tube, which is solid and entire. Abdomen about twice as wide as head, on average about two and a half times as long*wide; segments that overlap somewhat; sides nearly parallel to middle, then gradually tapering to base of tube. Tube about four-fifths as long as head, only slightly conical; straight sides; terminal spines shorter than the tube. Prothorax three-quarters as long as head and three-fifths as wide; fore coxa^ projects considerably beyond posterior angles. Tube two-thirds the length of the head and one-seventh as broad as the fourth abdominal segment; terminal spine as long as tube. This species therefore appears to unite the characters of these two genera, and as more emphasis is placed on the description of the female than on that of the male, I have preferred to include this species in the established genus Phla 'otkrips instead of creating a new generation for it. Tube four-fifthsas longas head; sides straight and slightly curving; breadth in the middle, one-seventh of that in the middle of the abdomen; .. end circle of bail along the length of the tube, very thin. S})ines on the sides ofal)domen blunt; abdomen.qu.it (miniform vidlowish brown (dark brown where the segments overlap). P^ja large, finely faceted, reniform above, inner edges parallel; ocelli small, approximate and located between the middle of the eyes. Abdomen a)) beyond two-thirds of the length of Ixxly, gradually tapering from the second segment to the tip; width at second segment, but slightly less than niesothorax. Head cylindrical, one and a half times as long as wide, about as wide as length of prothorax; cheeks almost straight and almost parallel, set with a few minute, slender spines; postocular ligatures short; head surface striated transversely. Antennae about at base, inserted below vertex, only about one and one-sixth times as long as head, and slender; the relative lengths of the segments as follows:. Light brown; eyes strongly faceted, crimson brown in certain lights; three basal abdominal segments dark brown above; segments 4, 5 and white; apical segments light brown, sutures dark; legs, except hind femur towards tips, white; .. wings striate, strongly bordered, without nerves, ground color]) rowed or hairy, with three transverse white bands, viz. e., the forewings have a white band at the base, the second at about two-thirds of their length, and the tips are white. The abdomen is concave on the upper side and is provided with a conical tube at the tip, which has a few bristles projecting from it. its peak. In one it is very]) of a bee-like spindle shape, the type is slightly elaborate, nine joints are visible, the top is decorated with a few hairs and is bluntly rounded at the tip; the other has the sides equal, the apex not at all produced, but very broadly rounded, only seven or eight joints vaguely defined. "A single species is known.". The prothorax is much larger than the head, the chest is very large, stout and fluffy; fore femur very strong, scarcely twice as long as wide; foretibipe also stout, a little longer than femur; the other legs are moderately .. stout, long, reaching )ie3" to the tip of the abdomen, with a few scattered, rather short, spiny hairs; the hind tarsi three-jointed, the hind joint smaller than the others, and altogether two-sevenths the length of the tibia?. Its legs, mainly used for running or crawling, would be few. if . any, modifications, while its wings, though certainly slender, were probably broad compared with those found in order to-daj^ and the hairs which happened to stand along their edges had begun to lengthen so as to some extent to compensate for the narrowness - branes. Consequently, wings would degenerate from disuse, and the movements of the insects on their feet would become slower, perhaps, and ]:) would probably be a distinct disadvantage in such a limited ha))itat, so that many influences would tend towards their reduction. A. Comparing the antenna in the three families will help us determine the order in which the families should be arranged. Only one character Avings of the extreme groups resemble each other—that is in the broad peaks. BIBLIOGRAPHY 224 PROCEEDINGS OF THE NATIONAL MUSEUM INDEX TO GENERAL SUBJECTS 234 PROCEEDINGS OF THE NATIONAL MUSEUM INDEX TO FOOD PLANTS EXPLANATION OF PLATP:S NORTH AMERICAN TJIY8AN0RTERA—HINDS.. MiddCdtlirips zoiiatm\, head, ])rothorax, antenna', and forelegs <>f fe-. Thrijis Udiuci, longitudinal-vertical section through anterior part of body showing shape of head and thorax and position of nervous system and alimentary canal. 242 PROCEEDINGS OF THE NATIONAL MUSEUMJ 84 PROCEEDINGS OF THE NATIONAL MUSEUM
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CHARACTERS OF TUBULIFERA (PLCEOTHRIPID7E)
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UNCLASSIFIED DESCRIPTIONS. ^
F08S1L THYHANOPTEKA
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