The beetle (fig. 12) varies in size from 13 mm. to 21.5 mm. in length, the measurements being taken from the tip of the mandibles to the ends of the elytra; the average length is about 19 mm., and the females are slightly broader than the males. The insect is strikingly marked with yellowish-white and blackish-brown hairs.
Head (figs. 15, 18 and 19).
The dead is a strongly chitinized capsule with most of the sclerites fused and only a few sutures showing. The epicranial suture is complete, and terminates in a pointed process at the dorsal surface of the occipital foramen. Hairs cover the head in patches; the chitin is blackish-brown and the hair patches yellowish, giving a mottled appearance to the head.
The vertex is depressed and the antennae are borne on slightly raised processes, which are surrounded by the eyes on the outer side. The post-clypeus is fused with the greatly reduced frons. The anteclypeus is membranous and bears long hairs. The gena on either side is slightly swollen posteriorly to the junction with the clypeus; between this swelling and the junction it bears a facet for the articulation of the ginglymus of the mandible and ventrally a cavity for the condyle of the mandible of that side. The genae do not meet ventrally, being separated by the gula. The latter is broader posteriorly, narrows slightly and then broadens out anteriorly; posteriorly it is separated from the genae by the gular sutures, and anteriorly bends downwards forming a depression before it curves forwards to carry the submentum. The occipital area has two indented lobes dorsally.
The eves are convex, crescentic in outline, and constricted medially; they curve round the base of the antennae posteriorly and come together more closely dorsally than anteriorly. There are hairs round
Fig. 1.–Larva: head, dorsal view. Fig. 2.—Larva: head, ventral view. Fig. 3.— Larva: left mandible, dorsal view. Fig. 4.—Larva: left mandible, ventral view. Fig. 5.—Larva; labium, maxillae and hypopharynx, dorsal view. Fig. 6.—Larva: labium, side view. Fig. 7.—Larva: labium and epipharynx, ventral view. Fig. 8.— Larva: head, side view. Fig. 9.—Pupa: last segments of abdomen, ventral view. Fig. 10.—Pupa: last segments of abdomen, posterior view. Fig. 11.—Pupa: left side of pupa.
Fig. 12.—Imago: male, dorsal view. Fig. 13.—Imago: right maxilla from an inside ventral aspect. Fig. 14.—Imago: right maxilla from side of attachment. Fig. 15.— Imago: side view of head. Fig. 16.—Imago: right galea, side view. Fig. 17.— Imago: right cardo. Fig. 18.—Imago: head, anterior view. Fig. 19.—Imago; head, ventral view. Fig. 20.—Imago: right mandible, ventral view. Fig. 21.—Imago: labium and hypopharynx, side view. Fig. 22.—Imago: labium, ventral view. Fig. 23.—Imago: labrum and epipharynx. ventral view. Fig. 24.—Imago; labium and hypopharynx, dorsal view.
Fig. 25.—Left wing. Fig. 26.—6th and 7th abdominal stergum of female, ventral. Fig. 27.—6th and 7th abdominal stergum of male, ventral. Fig. 28.—6th and 7th segments of abdomen of mule, dorsal. Fig. 29.—7th segment of abdomen of female, dorsal. Fig. 30.—Spicula gastralia, ventral. Fig. 31.—Tegmen, dorsal. Fig. 32.— Ventral view of tegmen and median lobe in natural position. Fig. 33.—Male reproductive system. Fig. 34.—Median lobe, dorsal. Fig. 35.—Median lobe, left side. Fig. 36–Chitinous rods.
Fig. 37.—Ovipositor, from left side. Fig. 38.—Ovipositor, dorsal, membranous tube silt up to expose end of ovipositor retracted within. Anus and rectum cut across to show anterior ends of coxites and vagina attachment to membranous tube. Fig. 39.—Ovipositor, ventral. Fig. 40.—Egg. Fig. 41.—Female reproductive system -right oviduct silt up, ventral view. Fig. 42.—Spermatheca and portion of the bursa copulatrix.
the margin giving the appearance of eye lashes; these are most strongly developed ventrally and postero-dorsally as well as anteriorly in the median line. The ommatidia are hexagonal and uniform.
The antennae are very long, longer than the body, and typically eleven-jointed. The scape is the thickest, the pedicle shortest, and the third joint longest. The first six segments, especially the first four of the flagellum, carry long setae posteriorly along their length. The basal colour of the antennae is a blackish brown, but white, yellow, brown, and black hairs arranged in bands give the antennae the characteristic banded appearance. The clothing hairs of the scape are brown, those of the pedicel blackish-brown, while the long setae on the scape are yellowish and on the pedicel black. In the next four joints, the clothing hairs proximally are white, and distally brownish-black; the long setae are proximally yellow, and distally black. The seventh joint carries a few long setae on the proximal posterior border; these setae are not as long as those of the other joints. The last five joints exhibit the same basal colour, becoming a little lighter toward the extremity; they are covered with short clothing hairs which are white at the base but otherwise blackish-brown. The joints are progressively shorter from the third to the eleventh, the latter being rounded at its tip; all articulate with their neighbours except the pedicle, which appears fused to the third joint. The scape articulates with the head by means of the antennary socket.
The lateral anterior inner parts of the labrum bear setae as well as the external portion. On the inside the median section is raised to form the epipharynx (fig. 23), the sides of which are supported by chitinous rods posteriorly.
The mandibles (fig. 20) are well developed, strong, hollow and curved, with a sharp cutting inner edge slightly serrated, and a broader outer edge which carries hairs; there is no tooth as in the larval mandible. The condyle is well developed and articulates in the socket of the gena which is ventro-laterally placed. The fronto-clypeal facet for the ginglymus is dorso-lateral. Both dorsal and ventral surfaces of the mandible are smooth; on the dorsal surface near the base of the inner margin of the mandible there is a small hollow or pit filled with short hairs; there is no crushing area. The mandibles are used for cutting the bark scissor-fashion and evidently the small pieces shredded off do not undergo further mastication, the gut being found to contain comparatively large pieces.
Each maxilla (figs. 13, 14 and 17) consists of a basal cardo (fig. 17) which is completely hidden from view when the parts are lying in situ; it is narrower basally and has a half turn, the line of attachment to the head being at right angles to the line of attachment to the stipes. The stipes is visible ventrally when the parts are in situ; it is roughly a rectangle and hairs are present along its outer margin. Antero-laterally the stipes carries the palpifer which bears the four-segmented palp; the connecting membranes are white and the joints of the palp blackish brown with comparatively few setae; this absence of setae is an unusual feature; the basal joint is the shortest, the next two the longest and broadened anteriorly, while the terminal one is obtusely pointed.
The stipes bears the two-pointed galea between the lacinia and the palpifer. The proximal portion or the blade of the galea (fig. 16) is narrower and triangular in cross section, while distally it broadens and flattens; it bears numerous hairs on the anterior end of the outer surface. The sub-galea is at right angles to the blade.
The distal portion of the lacinia, which is in two parts, has long hairs and is carried by the basal portion which is partly fused to the outer border of the sub-galea.
The labium (figs. 21, 22, and 24) consists of a mentum (Imms 3) or a submentum (Tillyard 10) bearing anteriorly two labial palpigers which carry the three-joined labial palps, the terminal joint of which is obtusely pointed; there are a few setae on all three joints. Joining the palpigers to the mentum is a slightly chitinized membrane hidden from view by the mentum when the parts are lying in their normal position.
The ligula is bilobed and flat anteriorly; it carries a few hairs on the ventral surface, while anteriorly, in the mid-line of the inner surface, there are numerous setae, which are shorter and denser posteriorly.
The hypopharynx anteriorly is a smooth median process on the floor of the mouth; posteriorly it widens and becomes more membranous.
The hind wings (fig. 25) are membranous and transparent, nearly half as wide as long, and when fully extended as in flight they are about four-fifths of the total length of the whole insect; they are covered by minute spines, longer along the posterior margin.
The venation of the wing follows the Cantharid type. The veins present are Costa, Subcosta, Radius, Radial sector, and R.2, R.3, R.4 and R.5, Media, M.1, M.2, Cubitus, Cu.1, Cu.2, Anal, A.1, A.2, A.3, and certain cross veins, m.-cu. being incomplete. The costa is reduced, being present only at the humeral angle, while the subcosta extends for about a third of the wing length.
R.1 is a large convex vein which runs more than two-thirds of the way down; a small vein is given off posteriorly to it which is presumably the radial sector; R.2 appears as a recurrent branch of the radius; M.1 and M.2 coalesce distally forming a loop (Cantharid type), and M.2 continues to the wing margin; the cubitus is incomplete, only the distal portion remaining with Cu.1, and Cu.2 continuing towards the margin; the proximal end of the media is thickened, which may represent the fusion of M. and Cu. at their basal ends; three anal veins are present at the base of the wing. Halfway down the length of A.1, A.2 either coalesces with it, or is joined by a cross vein to it, in which case the rest of A.2 is missing. A.3 is very broad at the base, narrows distally, but does not reach the wing margin. There is a small fragmentary transverse vein given off from M. which is probably m.-cu.; in some wings it is attached to M., in others it is free, but its other end is branched and is thus T-shaped. Between R.2 and M.1 there are several reduced veins. It was not possible to trace the development of the wings, so it cannot be said with certainty
which veins the reduced ones represent. Probably the vein running to the margin is the distal end of R.4 or represents R.4 and 5, and R.3 is the fragmentary vein lying between R.2 and M.1. If this is the case, there are then cross veins r.1-r.2, r.2-r.3, and r.3-m.1.
There are seven visible terga and five visible sterna in the abdomen. In the male a terminal segment is retracted within the abdomen, and in the female one or more of the terminal segments go to form part of the ovipositor. In the female the seventh tergite (fig. 29) is much larger than that of the male (fig. 28); it is as strongly chitinised as in the male, and there are two antero-median processes which lie below the tergites of the preceding segments and to which muscles of the ovipositor are attached. The seventh sternite (fig. 26) is much broader and longer than that of the male (fig. 27); there is a median longitudinal furrow which widens posteriorly and which is absent in the male, a character giving the easiest method of distinguishing the sexes.
The Male Reproductive Organs (fig. 33).
The testes are paired, and in each, held together by a membrane, there are two lobes which are round flattened bodies, the centre being thinner than the sides. The greatly coiled vas deferens, formed by the union of the two small vasa efferentia which leave the inner hollowed centre of each lobe of the testes, lies between the lobes and leaves the surrounding membrane about the point where it is joined by the accessory gland and seminal vesicle. In Saperda carcharias, belonging to the same sub-family, instead of a separate vas efferens for each lobe there is only one which passes through the second lobe.
The accessory gland, a comparatively small, blind structure with the anterior end bluntly pointed, is slightly swollen before it narrows and joins the vas deferens.
The seminal vesicle is very narrow anteriorly and greatly coiled, but before joining the vas deferens it swells out and is usually twisted three or four times.
The ejaculatory duct, greatly coiled and very long, is surrounded by a thick muscular coat posteriorly. Near its termination it is supported by two chitinous rods (fig. 36) which are long, round, and narrow, being attached at their basal ends to the beginning of the internal sac into which they project; these rods are evidently structures for strengthening the protrusile end of the ejaculatory duct, and presumably form the transfer apparatus.
The internal sac, a very long structure, lined with patches of small spines, is divided into three parts by two well-marked transverse folds, the anterior part being very narrow and the two posterior ones much larger. The beginning of the second part is slightly bulbous, and muscles are attached to it. The third part is nearly equal in length to the other two together, and widens to about three times its original width before the attachment of its posterior end to the inside posterior end of the median lobe, where it opens to the exterior through the median orifice. In the 2nd and 3rd parts, dorsally and
ventrally, there are two longitudinal bands of granular thickening which narrow at the transverse fold between the two parts and which terminate about halfway down the third part.
The median lobe (figs. 32, 34 and 35), a curved hollow structure with a pair of anterior struts, is formed by a dorsal and a more strongly thickened ventral sclerite which join latero-anteriorly, and are connected latero-posteriorly by a slightly chitinized membrane. The ventral sclerite is much broader than the dorsal, and not so curved. The internal sac enters the median lobe through a median ventral foramen over which the two struts curve dorsally, the ventral sclerite passing up on either side of the foramen to join the dorsal sclerite. The internal sac is attached internally to the posterior end of the median lobe separating the two sclerites, each of which forms a lip to the median orifice. The internal sac is not attached to the extreme tip of the ventral sclerite, which forms consequently a more marked lip towards which the tip of the dorsal sclerite curves down. When tie internal sac is everted the two sclerites are forced apart to allow the internal sac to be pushed through.
The tegmen (figs. 31 and 32) surrounding the median lobe is ring-shaped with a pair of well-developed lateral lobes carrying a few stiff hairs on their distal ends. The basal piece has possibly fused with these lobes and is not developed to the extent that it is in S. carcharias; basally to this the lateral lobes are joined. To the outside of lateral projections of the basal piece extending inwards, but not meeting in the midline, are attached a pair of ventral struts which meet basally; these struts are comparable with the stout chitinous arch described by Ritchie (5). The lateral projections and dorsal fused parts appear to be all that are chitinized of the basal piece. According to Sharp (7) the chitinized condition of some parts is secondary to the membranous condition; if this were to hold for the basal price it might be that the ventral part is membranous, and thus the membranous basal piece would be in the same position as the chitinized basal piece of S. carcharias. There would be no distinction between the membranous basal piece and the second connecting membrance.
The spiculum gastrale (fig. 30), a curved chitinous rod forked posteriorly, but varying in shape in different individuals, is found lying below the median lobe and the tegmen. The anterior end is abruptly curved towards the dorsal surface or, more usually, slightly to one side; the posterior end is bi-fid and bends towards the dorsal surface.
The Female Reproductive Organs (fig. 41).
The two ovaries, one on either side of the abdomen consist each of twelve egg tubes, each tube ending in a terminal chamber which is bottle shaped and has a filament at its apex; these filaments come together at a distance away from the end cells of about half the length of the tubules. The ovaries are arranged in a circle, and open in to the swollen end of the comparatively short oviduct.
The thin-walled accessory gland is a long coiled tube, narrowing anteriorly to an obtuse apex. The secretion which entirely fills the cavity is probably that which is used by the female in sealing the
oviposition holes. The opening of the narrow chitinous tube which connects the gland to the bursa copulatrix is situated at the apex of a protuberance projecting into the latter.
The spermatheca (fig. 42) is a round, short, blunt, chitinous tube with a very narrow duct at right angles to it which connects it to the thick-walled bursa copulatrix. The inner surface of the spermatheca is produced into spines, and the cavity is often completely filled with sperms. The spermatheca runs parallel to the bursa copulatrix, to which it is attached by muscles, especially at its free end.
The bursa copulatrix, the walls of which are very muscular, narrows slightly, coils three or four times when it straightens out and becomes gradually much wider, while at the same time the wall becomes thinner and less muscular, though there is a strong muscular investment for the full length. The bursa copulatrix lies between the oviducts, and, narrowing, enters the vagina dorsally.
The oviducts pass above, and lie between, the muscles which originate on the head of the spiculum ventrale, and which are attached to the anterior fold of the membranous tube of the ovipositor. The ducts join ventrally in the median line, to form the common oviduct lying between the spiculum ventrale and the ovipositor.
The beginning of the vagina is the widest portion of it; ventrally, from the sides of this wider part, there are given off a pair of membranous flaps, each of which has a slight chitinous thickening at its base towards its ventral corner; the common oviduct enters ventrally between these flaps, while the bursa copulatrix enters dorsally at the same level.
There is a great development of muscles round the beginning of the vagina; muscles to the ovipositor are attached to it, the ear-like membranous flaps giving a greater area for attachment. The vagina curves, and turns forwards, to recurve and enter the ovipositor; it continues for a short distance before it opens between the ends of the ovipositor.
The ovipositor (figs. 37, 38 and 39) consists of a folded membranous tube, and of several associated sclerites which form a sheath round the posterior end of the membranous part. The apex of the ovipositor consists of two slightly chitinized protuberances, probably the coxites described by Tanner (9); their ends are more strongly chitinized and each carries a tuft of short hairs. These hairs, or the more strongly chitinized tips of the coxites, may represent the styli described by Tanner and Verhoeff (11). Halfway down the length of the coxites, and between the two, there is a membranous flap (presumably the vulva described by Tannar) which protects the opening of the vagina. These processes or coxites are continuous with the membranous tube, the tube being folded at the point where they are attached to it. The anal opening is found dorsally above the coxites. There are certain tufts of short bristle-like hairs on the dorsal and ventral surfaces of the coxites beyond the opening of the vagina. There are also long narrow hairs on the inner margins of the coxites, and on the membrane between the two coxites covering the vagina. The tip of the ovipositor is capable of being pushed out between the more greatly chitinized sheath of the posterior part.
The large dorsal sclerites of the sheath of the ovipositor are united in the median line by a less strongly chitinized membrane They pass round the side and become much narrower, their ventral portion being very slight. There is a thin rod-like area which is more strongly chitinized, and which lies on either side of the mid-ventral line.
The saddle-shaped lateral sclerites are most strongly chitinized and are attached medially, on their inner surface, to the dorsal sclerites They are thickest medially, and ventrally spread out slightly but do not meet each other. The membrane which is attached to the last sternite and tergite of the abdomen is attached at its other end to the posterior margins of the lateral sclerites. From these sclerites numerous muscles arise.
Ventrally there is a rod-like sclerite in the median line with a slight fork at its posterior end. The dorsal and the ventral sclerites are formed into a continuous sheath by membrane; in this membrane there is a pair of longitudinal bands more strongly pigmented than the surrounding membrane. Near the posterior end of this membranous tube there are certain areas on which numerous setae are carried.
The chitinous rod (Ritchie) or spiculum ventrale (Verhoeff) (11) and Schedl (6) extends into the abdominal cavity, passing from the ventral towards the dorsal surface inwards, and reaching into the metathorax; this rod is hollow posteriorly, and opens to the exterior on the central surface, where it is covered by a membranous fold or pocket. The spiculum ventrale varies in shape in different specimens; it is usually not quite straight, and sometimes has a more strongly marked head, but in all cases it is of the same relative length to that of the body of the insect.