THE LIFE HISTORY of SCHINIA SEPARATA (NOCTUIDAE) 5 Chinia
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VOLUME 25, NUMBER 3 177 THE LIFE HISTORY OF SCHINIA SEPARATA (NOCTUIDAE) D. F. HARDWICK Entomology Research Instihlte, Canada Department of Agriculture, Ottawa, Ontario 5 chinia sepamta (Grote, 1879) 1 is distributed in western North America from southern British Columbia and Alberta southward to southern Cali fornia. In the Intermountain Basin area, it feeds in the larval stage on the buds and blossoms of the sagebrush, Artemisia tridentata Nut·t. (Figure 2). The moth is also common in some areas of the Great Plains in which sagebrush does not occur but in which the hoary sagebush, Artemisia cana Pursh. is abundant. Presumably in these grassland areas, the latter species of Artemisia serves as food plant. The adult is a late-summer flier and is present in most areas of its range during August and the first half of Sep tember. In the Intermountain Basin the period of adult activity is syn chronized with thc budding period of the sagebrush and the moth flies progressively latcr in the season with decreasing altitude and latitudc. Behaviour Schinia separata is a nocturnal species, and the eggs are deposited in the buds of Artemisia only at night. Three wild-caught fentales deposited a mean of 91 cggs and the maximum deposited by a single female was 119. The behaviour of the ovipositing female sepamta was described in my 1958 revision of the elliptoid-eyed Schinia: "The female alights on a spray of the still tightly closed buds and crawls over it, her abdomen arching ventrally. Having arrived at a site that is apparently suitablc, she secures herself by grasping buds and stems firmly with clawed tarsi, and begins an elaborate exploration with the ovipositor. Thc abdomen is arched ventrally and anteriorly, often being thrust for ward so as to protrude through the legs. The ovipositor, on encountering the small hard bud, feels the surface and probes it with short, delicate stabbing movements. When the edge of one of the stiff outer sepals of the bud is encountered the blade of the knife-like ovipositor is forced against this edge and the moth, by rapid lateral movements of the abdomen which cause her whole body to vibrate inserts the ovipositor valves be neath the sepal. In this manner the egg is deposited within the bud at or between the bases of the innermost sepals. The ovipositor is then with drawn and the moth usually flies to another bud cluster before the process is repeated." I I cannot distinguish separa.ta from Schinia acutilinea (Grt.) (1878, Can. Ent. 10: 232) with any degree o f certainty, hut hesitate to synonymize the two without fuller study. If the two names do represent the same species, acutilinea ,",vill take precedence. 178 JOURNAL OF THE LEPIDOPTERISTS' SOCIETY Figs. 1, 2. Schinia separata (Crt.) and its food plant. 1, Adult, Oliver, B. C.; 2, Artemisia tridentata Nutt. The egg is oftcn grossly distorted in shapc as a result of being inserted beneath the sepals among the developing petals of the still tightly closed bud. The majority of eggs hatch on the seventh day after deposition. The newly hatched larva immcdiately attacks the succulcnt tissues of the de veloping bud. The larva usually completcs its first stadium in the initial bud, but during the second stadium migrates to an adjacent bud which it cnters by boring a hole through the apex where the sepals are thinnest. The anterior two pairs of larval prolegs are reduced in size in the second and third instars and the larva mixed with a looping motion similar to that of catocalinc larvae. During the third stadium the larva ceases to conceal itself completely within thc bud and feeds from an exposed po sition on the stem. The larvae continuc to attaek the buds at the apex, however, where the tissues are softer. Nineteen of 50 individually reared larvae matured in five stadia, the remainder in six. The mature larva tunnels into the ground to form its pupal cell and it is in the pupal stage that the insect remains throughout the majority of the year. Descriptions of Stages The following descriptions of immature stages were based on the prog eny of three females taken in the Okanagan Valley near Oliver, B. C. The larvae were reared individually at room temperature on the buds and blossoms of Artemisia tl'identata. Rearing techniques employed were those used by Hard wick (1958). The estimate of variability following the mean for various values is the standard deviation. Unfortunately the larvae of sepamta being reared had to be removed from the Okanagan Valley to Ottawa during the median stadia. Although flowering heads of the food plant were shipped by air express to Ottawa, VOLUME 25, NUMBER 3 179 the larvae did not develop normally and the ultimate stadiurn became greatly protracted. The larvae eventually died without pupating. The developmental data is therefore not complete, and the durations listed for the median stadia may be somewhat attenuated. Adult. (Fig. 1). Head and thorax silvery-fawn to greyish-fawn. Abdomen silvery-fawn or silvery-grey. Underside of body dull pale grey. Forewing olivaceous fawn marked with white; forewing occasionally with a rosy suffusion. Transverse anterior line white, usually smooth, arched strongly and acutely outward. Basal space olivaceous fawn, longitudinally streaked with white and with a dark margin along t.a. line. Transverse posterior line white, generally smooth, exeurved around cell, then usualJy straight to inner margin. Median space fawn, paler than basal space, usually with a pale longitudinal streak through cell. Orbicular spot not defined. Reniform spot usually indicated only as a narrow dark shade. Subterminal line white, irregular, closely approaching and occasionally fusing with outward arc of t.p. line. Subterminal space darker than median space and usually darker than basal space. Terminal space pale fawn. Fringe whitc checkcred with fawn. Hind wing white with dark brown discal mark and dark-brown outer-marginal band. Outer-marginal band with a white streak or blotch toward anal angle. Fringe white, usually with a pallid brown inner line. Undersides of both wings white or pallid grey, marked with brown. Forewing with small, dark-brown, orbicular and reniform spots, and with a paler brown subterminal band. Hind wing with a narrow dark-brown dis cal spot and an evanescent outer-subterminal band. Fringes of both wings white. Expanse; 26.4:±: 2.2 mm (92 specimens). Egg. Very pale greenish-yellow when deposited. Losing some of greenish colouring on the second day, then remaining essentially unchanged for remainder of incubation period. Mandibles and ocelli becoming visible through chorion a few hours before hatching. Incubation period; 7.2:±: 0.7 days (157 eggs). First-Stadilllll Larva. Head translucent blackish-grey. Pro thoracic and sunmal shields somewhat paler than head. Trunk pale greyish-white becoming stained with yellow or green after larva begins to feed. Thoracic legs and proleg shields dark smoky-brown. Head width; 0.240:±: 0.011 mm (25 larvae). Duration of stadium; larvae maturing in five stadia, 5.3 :±: 0.7 days (19 larvae) ; larvae maturing in six stadia, 5.1 :±: 0.4 days (31 larvae). Second-Stadium Larva. Head varying from dark brown to medium light brown. Prothoracic shield concolorous with trunk except for some pale-brown flecking. Suranal shield concolorous with trunk. Trunk with a chalky opacity uncommon in second-stadium noctuid larvae; varying from a blotchy yellowish-grey to a blotchy greenish-grey. Thoracic legs and proleg shields brown. First two pairs of anal prolegs smaller than remaining pairs. Head width; 0.319:±: 0.010 mm (25 larvae). Duration of stadium; larvae maturing in five stadia, 4.0:±: 0.6 days (19 larvae); larvae maturing in six stadia, 4.1 :±: 0.6 days (31 larvae). Third-Stadium Larva. Head pale fawn grey. Prothoracic shield whitish-grey marked with brown. Suranal shield essentially undistinb'Uished from trunk. Mid dorsal area dull, dark brownish-grey. Subdorsal area white or pale grey with a pair of dark-grey median lines. Supraspiracular area dark greyish-brown, with a discon tinuous, white or pale-grey median line. Spiracular band white or pale grey with a darker-grey or brown median shade. Suprapodal area similar in colour to supra spiracular area. Mid-ventral area varying from greenish-grey to brownish-yellow. Head width; 0.51:±: 0.02 mm (25 larvae). Duration of stadium; larvae maturing in five stadia, 6.1 :±: 1.2 days (19 larvae); larvae maturing in six stadia, 4.9 :±: 1.1 days (31 larvae). 180 JOURNAL OF THE LEPIDOPTERISTS' SOCIETY Antepenuhimate-Fourth-Stadium Larva. Head fawn-grey heavily marked with medium brown. Prothoracic shield white, usually heavily suffused with brown; heavily suffused shields with three well-defined longitudinal white lines. Sunmal shield eoncolorous with trunk. Mid-dorsal band dark-brown with a pale median shade. Sub dorsal area pale grey or white with a pair of pale-brown median lines. Supraspiracular area brown with a badly broken white or pale-grey median line. Spiracular band white with an irregular light-brown median line. Suprapodal area coneolorous with supra spiracular area. Mid-ventral area pale grey mottled with light brown. Head width: 0.74 ± 0.03 mm (44 larvae). Duration of stadium: 5.7 ± 1.1 days (31 larvae). Penultimate-Stadium Larva. Head creamy white mottled with mauve-brown. Prothoracie shield white with a broad median and a pair of narrower submarginal lines of mauve-brown. Suranal shield poorly distinguished from remainder of trunk. Mid dorsal band dark brown with a pale median shade. Subdorsal area white with a pair of irregular, pale-mauve median lines. Supraspiracular area mauve-brown, paler dor sally than ventrally; mottled mesally with white.