DRONE WING, VENTRAL SURFACE

BOTTOM LEFT. Hind wing, ventral view, at low magnification. Several veins intersect in this field. (x90)

TOP LEFT Ventral view, near the tip of hind wing. Exceedingly small, cuticular spines randomly arise in this area. Some scattered pits are also visible. (x 420)

TOP RIGHT. Forewing tip, ventral view. Numerous scattered small, blunt cuticular spines are found on this surface. The pits represent the bases of the short counterpart spines arising on the reverse surface of this wing. ( x 130)

BOTTOM RIGHT. Higher magnification of the ventral forewing in the top right micrograph. The spine density is 1/900 micro m^2. (x 750)

DRONE WING HOOKS

BOTTOM LEFT. Leading edge of the hind wing The hooks engage the posterior margin of the forewing only during flight, when the forewing and hind wing beat as one. Microtrichia are abundant over the wing surface. (x 136)

BOTTOM RIGHT. Non-hook-bearing portion of the hind wing in the bottom left micrograph. Socketed hairs, both long and very short, project from this vein. ( x 800)

TOP RIGHT. Photorriontage of the ventral forewing hind margin, around which the hooks engage, and the hooked leading edge of the hind wing. (x 110)

TOP LEFT. Close-up of the wing hooks. These are somewhat medium than those of the worker. Socketed small peg organs are abundant on the surface engaged by the trailing edge of the forewing. (x 720)

DRONE FORELEG

MIDDLE. Photomontage of the entire left foreleg. Proximally to distally, after the coxa (first leg segment from the body) are the trochanter, femur, tibia, basitarsus (with antenna cleaner notch), three short tarsal segments, pretarsus, and claws. ( x 31)

TOP. Prothorax, ventral view. Two scaled coxae (medioanterior surfaces) abut on either side to a smooth-surfaced basisternum. Mechanoreceptor hair plates of the coxae engage the lateral basisternum (arrows). (x 168)

BOTTOM LEFT Lateral edge of the coxa extending diagonally through the center of the field. A mechanoreceptor hair plate on the lateroanterior surface engages the adjacent sternum. (x 93)

DRONE FORELEG, CLOSE-UP

TOP LEFT. Tibia-basitarsus joint, the region of the antenna cleaning apparatus (comb). The fibula (upper right) is a clasplike spur that closes over the semicircular toothed notch (rimmed with comblike hairs). The antenna is inserted in this enclosure and drawn upward to clean debris from its cuticular receptors. The fibula fits into the proximal portion of the basitarsus to form an embrace around all antenna surfaces. (x 161)

TOP RIGHT. Dorsal view of the fibula showing the notch of the antenna cleaner. From this angle it is apparent that the fibula is contoured into several lobes to make better contact with the circular (in cross section) antenna. (x 195)

MIDDLE RIGHT Higher magnification of the tibia-basitarsus joint. A patch of unusual cuticular setae is on the tibia (see the top right micrograph). These setae have twisted blunt tips with several parallel ridges along the long axis of the hair. ( x 496)

BOTTOM RIGHT. Femur-tibia joint. The intersegmental membrane is studded with short, acute cuticular spines. (x 770)

BOTTOM LEFT Femur-tibia joint. The tibia is very flexed relative to the femur. The long, straight, unbranched hairs of the compound eye are in the far background. (x 280)

DRONE FOREFOOT AND HIND FOOT

TOP LEFT. Survey of the hind foot. The claws are simple, unlobed, hollow hooks fringed with (probably sensory) hairs. (x 100)

TOP RIGHT. Arolium (from the hind foot) showing its hirsute medial surface and glabrous, grooved exterior (compare with Plate 1.34, the queen forefoot and hind foot). Three long spines hang down from the median sclerite above. ( x 400)

MIDDLE. Higher magnification of the hairs lining the medial surface of the arolium. (x 4,250)

BOTTOM. Forefoot (prothoracic foot). In the foreground is the median sclerite, from which extend four stout, slightly curved spines. The basal portions of the right and left claws are on either side of the median sclerite. The ventrodistal margin of the fifth tarsal segment arises over the claw bases and median sclerite. Left and right sensory hair plates are evident above the claws; when the claws are raised they contact these putative mechanoreceptors to inform the drone whether its claws are extended or flexed. (x 510)

DRONE MIDDLE LEG

TOP. Photomontage of the left middle (mesothoracic) leg. The coxa is obscured but, proximally to distally, the trochanter, femur tibia (with spine or wax spur pointed downward), basitarsus and three additional tarsomeres, and the pretarsus with claws are visible. ( x 31)

BOTTOM RIGHT. tibia-basitarsus Joint. This is a monocondylic (single point) articulation. The relatively large size and stoutness of the tibial spine are evident. ( x 93)

BOTTOM LEFT. Tibia-basitarsus Joint. This view and magnification make apparent the differences in the cuticular surfaces between the scalelike tibial base, the pebble-grained tibial spine, and the smooth head of the basitarsus. The two forms of setae (branched and simple trichoid) on the tibia are visible at this articulation, as well as the scales on the mtersegmental membrane at this Joint. ( x 355)

DRONE LEG BASES

TOP RIGHT. Bases of the middle (mesothoracic) and hind (metathoracic) legs (the abdomen is to the left). In the foreground, proximally to distally, are the coxa, trochanter, and a small portion of the femur of the hind leg. The arrow indicates the trochanter-coxa Joint, which is further magnified in the bottom right micrograph. ( x 60)

TOP LEFT. Scale-studded intersegmental membrane (center) covering the articulation between the hind coxa and trochanter. The proximal surface of the trochanter has about two dozen short, sharp, socketed hairs that may be mechanoreceptors that contact the coxa In the course of locomotion and inform the nervous system as to leg position. (x 240)

BOTTOM. Trochanter-coxa joint (arrow in top right micropraph (x 298)

DRONE HIND LEG

TOP. Photomontage showing entire left hind (metathoracic) leg and the coxa, trochanter, and femur of the adjacent leg. At the distal extremity of the completely exposed leg are the two claws of the pretarsal segment, followed proximally by four tarsal subsegments, the most proximal of which connects to the elongate flattened basitarsus. The basitarsus articulates with the tibia. The femur, trochanter, and coxa are in a distal to proximal succession. No pollen gathering or transfer modifications such as on these segments in 'the worker are present on the drone hind leg. Compare with Plates 2.28, 2.29, 2.30, and 2.31. (x3l)

MIDDLE LEFT. Lateral view of the metathoracic pretarsus (distal edge at the top). The setae are relatively sparse and extremely short. (x 37)

BOTTOM LEFT. Medial surface of the metathoracic pretarsus (distal edge at the top). This side is characterized by a dense pile of rather long setae. (x 34)

DRONE HIND FOOT

BOTTOM. Pretarsus and fifth tarsal segment. The claws gape widely to better reveal the soft, pursed medial lobe (arolium). Five long, curved setae emanate from the median sclerite, which, in turn, articulates with the last tarsal segment. Rows of short trichold sensilla descend over the dorsum of the last tarsal segment. (x 180)

TOP LEFT. Three tarsal segments of the hind (metathoracic) foot. The planta (seen here as the upper surface, which is the best orientation for the viewer), covered with short hairs, contacts the substratum. (x 110)

TOP RIGHT. Lateral view of the pretarsus and last (fifth) tarsal segment showing the contracted nature of the arolium and the upright orientation of the medial sclerite. The five trichoid sensilla arise from the medial sclerite at different levels. (x 143)

Lateral view of the drone gaster (abdomen)

DRONE PETIOLE, DORSAL VIEW

TOP. Slightly curved anterior margin of the propodeum, at the top of the field. The membranous connective of the (dorsal) petiole is in the center. (x 100)

MIDDLE LEFT. Close-up of the dorsal membranous region in the top micrograph, with the connective cut. Longitudinal wrinkles and copious scales are prominent in this region. (x 168)

MIDDLE RIGHT. Apodeme for wing muscle attachment, immediately anterior to the petiole. ( x 234)

BOTTOM. Higher magnification of the cuticular scales of the dorsal membranous wall of the petiole. Five to seven spines of several lengths project from each scale. (x 3,230)

DRONE PETIOLE, ABDOMEN DETACHED

TOP LEFT. Cross-sectional cut through the membranous petiole. The longitudinally seamed, scaly membrane (at 12 o'clock) and the thoracic cavity immediately beneath are exposed. Two sizable muscles with sheaths (at 3 and 9 o'clock) are visible; these assist in elevating the abdomen. (x 50)

TOP RIGHT. Reverse view of the top left micrograph showing the crosssectioned anterior end of the abdomen (gaster). The arrow points to the hair plate that is further magnified in the middle right micrograph. (x 50)

MIDDLE RIGHT. Dorsolateral hair plate of the petiole (arrow in top right micrograph). These mechanoreceptors monitor the gravitational pull of the gaster onto the thorax via the petiole. The socketed, unbranched hairs are mechanosensors. (x 300)

BOTTOM RIGHT. Higher magnification of the setae of the hair plate. (X 1,000)

BOTTOM LEFT. Longitudinal section through a cuticular spur in the petiolar region. The laminated appearance of the exocuticle is apparent. (x 8,640)

DRONE PETIOLAR HAIR PLATE, OBLIQUE VIEW

BOTTOM. Petiole, the junction between the first and second abdominal segments. This joint ensures great flexibility of the abdomen relative to the thorax. Monitoring this movement and providing the bee with information on the alignment of the thorax to the abdomen relative to gravity are several (mechanoreceptor) hair plates that are externally placed proprioceptors. One such hair plate is visible; the setae (sensilla) probably make contact with the dorsal wall of the petiole of the first abdominal segment. The black and white diagonal bar indicates the alignment of body segments (the head is to the upper left). (x 85)

TOP. Higher magnification of the contact zone between the hair plate receptors and the dorsal petiole. These four dozen sensory hairs are arrayed in various directions, so several of them contact the petiolar protuberance at any one time at any degree of flexion, which ensures a constant monitoring of abdominal position. ( x 430)

DRONE SPIRACLES

TOP. Photomontage showing primarily the first (propodeal) and second segments of the abdomen (dorsum at the top). Spiracles are visible (arrows) on these two segments. The wings have been removed. (x 31)

MIDDLE LEFT. Spiracle on the first abdominal segment at moderate magnification. This spiracle is somewhat medium than the others, and its elongate-oval rim differs from the more rounded appearance of the succeeding spiracles. ( x 63)

BOTTOM LEFT. Close-up of the first abdominal spiracle. The operculum (plate) covering this spiracle has been damaged in specimen preparation; in the intact bee this plate can be pulled down by an occlusor muscle, much like a window shade, thus shutting off this spiracle from the outside. The operculum is never completely open and its excursion is not large, so this situation permits only a minimal aperture. (x 170)

MIDDLE RIGHT. Two spiracles, one each on the second (left) and third (right) abdominal tergites. The more circular nature of these openings is evident. These spiracles are noticeably medium than those of the worker and queen. ( x 3 1)

BOTTOM RIGHT. Higher magnification of the third abdominal spiracle. The circular depression in the cuticle leads to an oval pit (lower right) that connects directly to the underlying trachea via a valve mechanism capable of occluding the spiracle atrium from the trachea. The branched hairs and valvular apparatus may be barriers that keep mites from entering the trachea through this spiracle. ( x 250)

DRONE SPIRACLES, CLOSE-UP

TOP. Survey of a portion of the second and third abdominal tergites showing the spiracle on the third. The posterior margin of the second abdominal tergite, which is sparsely covered with branched body hairs, is visible on the left. On the anterior margin of the third tergite are few setae, but the teardrop-shaped spiracular opening is surrounded by socketed hairs on its dorsal, ventral, and posterior margins. (x 175)

BOTTOM LEFT. Close-up of the spiracular opening. Inside the spiracle is the cuticular atrial wall, which bulges out somewhat and is covered with very short hairs. Atmospheric air passes over these finer setae and gains entrance to the trachea directly behind the atrium via a small channel. This canal can be opened when the muscles of its valve relax. (x 400)

BOTTOM RIGHT. Higher magnification of the small, unsocketed hairs of the medial wall of the spiracular atrium. The function of these hairs may be to remove particulate matter from the airstream. ( x 800)

DRONE ABDOMEN, DORSAL SURFACE

TOP. Photomontage of the dorsal portion of the left abdomen. About half of the second, third, and fourth abdominal tergites are visible in their total lateral expanse. (x 40)

BOTTOM LEFT. Higher magnification of a sector of the lateral surface of an abdominal tergite showing the furrowlike cuticular relief. Sparse, unbranched, socketed hairs are visible. The pores (at 4 and 10 o'clock) are probably orifices through which hairs once projected. (x 775)

BOTTOM MIDDLE. Highly magnified area of abdominal tergite showing both socketed smooth setae and a branched body hair. A pore is visible (arrow). (x 1,400)

BOTTOM RIGHT. Higher magnification of a cuticular pore on an abdominal tergite (arrow in bottom middle micrograph). This orifice has founded lips and no cuticular lid. (x 14,000

DRONE GENITAL ORIFICE

TOP LEFT. Terminal segments of the abdomen, frontal view. Two (paired) penis valves clasp the phallotreme, in which the penis is barely visible in its inverted position. Lateral to each of the penis valves is a "bewhiskered" paramere. Dorsal and ventral to the penis valves are sectors of intersegmental membrane. Within the dorsal intersegmental membrane (left), just above the left paramere, is the greatly reduced ninth tergite. The sclerotized "roof" for these organs is called the eighth tergite; immediately below the apex of that roof is a black crescent, the anus. Just below the anus is a platelike area called the proctiger. The eighth sternite forms the ventral V-shaped enclosure for these terminalia. ( x 40)

TOP RIGHT. Cuticular sculpturing of the intersegmental membrane surrounding the paramere-penis valve complex. (x 484)

BOTTOM. Higher magnification of the left paramere in the top left micrograph showing kinds of setae that arise on the parameral plate and lie over the left penis valve. Nine setae also arise from the lateral portion of the paramere. Immediately above and to the left of the paramere is the very small ninth tergite. The eighth tergite and sternite form the upper and lower diagonal sclerite margins respectively. (x 168)

DRONE GENITAL ORIFICE, INTERIOR VIEW

BOTTOM RIGHT. Frontal view of the terminal segments of the abdomen. Because of collapse of the last segments, the proctiger and anus are hidden under the eighth tergite, whose arched posterior margin is visible at the top of the field. The arrow points to the phallotreme, which is further magnified in the bottom left micrograph. (x 75)

BOTTOM LEFT. Phallotreme, the external opening of a deep endophallic pouch (arrow in bottom right micrograph). (x 510)

TOP. Cuticular scales on the dorsal aspect of the last (seventh) tergite. Each scale has four to six spinelike processes in essentially two size classes. (x 1,085)

DRONE GENITALIA

TOP LEFT. Vestibulum (bottom of the field). On either side of the vestibulum are the lateral horns or cornuti (arrows). The principal feature is the cervix of the tubelike penis. Chevronlike sclerites cover the ventral wall of the cervix. ( x 3 1)

MIDDLE LEFT. Base of the genitalia, located immediately below the field in the top left micrograph. The ventral plate of the vestibulum of the penis is covered with flexuous setae. On both sides of the vestibulum are the cornuti (external genital lobes). (x 31)

BOTTOM. Tufts of spicules on the medial wall of the cervix of the penis. (x 441)

TOP RIGHT. Higher magnification of the wall surface of the male genital duct. (x 300)

MIDDLE RIGHT. Surface of the horn (cornutus). The dorsal and lateral surfaces are papillate while the ventral surface is relatively smooth with longitudinal folds. (x 100)

SPERM

TOP LEFT. Floor of the cervix of the penis. Profuse small spines (spicules) line this intima. Several slender sperm are barely visible lying atop the spicules. (x 241)

BOTTOM LEFT. Massed, intertwined spermatozoa. (x 3,900)

TOP RIGHT. One entire sperm. (x 700)

UPPER MIDDLE RIGHT. One sperm head. The small nodules of the head are probably a manifestation of the acrosome. (x 16,000)

LOWER MIDDLE RIGHT. Head (right) and tail (left) of a sperm. (x 3,000)

BOTTOM RIGHT. Higher magnification of the sperm tail. The linear grooves may relate to the interspaces between adjacent peripheral microtubule singlets in the axoneme of the tail. (x 10,000)