Pupal Chambers Research Articles

Host Associations of Specularius Impressithorax (PIC) (Insecta: Coleoptera: Bruchidae) with Species of Erythrina (Fabales: Fabaceae)

Seeds of species of Erythrina are seldom damaged by insects because toxic amino acids and alkaloids are present in the cotyledon. No seed beetles (Bruchidae) are known to attack seeds of Erythrina in the New World. The African bruchid, Specularius impressithorax (Pic), has been recorded in 7 species of Erythrina (including 2 species introduced into South Africa from the Neotropics) in Africa and India. Distribution of S. impressithorax and its host species are listed. The beetle family Bruchidae (seed beetles) is widespread throughout the world, and species are especially numerous in tropical and subtropical regions. Larvae in this family without exception feed in seeds, but adults are pollenophagous, often feeding in flowers of plants other than the larval host plant. Eggs are deposited on the surface of the seed pod, or in some cases on the seed itself, and the newly hatched larva bores through the valve and/or seed wall into the cotyledon. All larval instars are spent in the cavity excavated by feeding activities, and the cavity in most cases is subsequently used as a pupal chamber. Following eclosion, the adult either chews an exit tunnel through the seed coat, or in some cases emerges through a tunnel excavated to the surface by the larva. Exit holes of bruchids are round and cleanly cut whereas those of other insects are ragged and irregular. The majority of known host associations of bruchids are in the order Fabales. Many bruchids are host specific (a species of bruchid preferring only one host species), but the more prevalent relationship is a species of bruchid being associated with two or more species in a plant genus. Some bruchids are less discriminating and may be associated with species in several plant genera, or even several plant families. Certain toxic compounds in seeds are effective deterrents to bruchid attack or development. A few legumes are entirely free of bruchid infestation, apparently due to the presence of toxins-e.g., Gliricidia sepium (Jacq.) Steud, Gymnocladus dioica (L.) Koch, and Robinia pseudoacacia L. (Janzen, 1969), but in others, e.g., Abrus precatorius L., Dioclea megacarpa Rolfe, Oxytropis spp., Astragalus spp., Enterolobium cyclocarpum (Jacq.) Griseb., certain species of Erythrina, one or more species of bruchids have either developed detoxification sys

Scotch Pine, Pales Weevil and Northern Pine Weevil Control, Atwood, PA, 1978

Abstract A stand of 1.5-2m Scotch pine Christmas trees was used for insecticide evaluation. The plantation was partially harvested in 1976 and 1977. Pretreatment weevil populations were noted (on April 17) by inspecting for adults in the duff, on stumps, under trunk end pieces left from harvest and old pupation chambers. A few weevils were active and ovipositing. A tree row with at least 7 new stumps (under 1 year old) was treated as one replicate/treatment. Treatments were replicated 4 times in a randomized complete block design. Each stump received 4-6 02 spray consisting of insecticide in kerosene (except Penncap-M in water) applied with a compression sprayer April 17. Temperature was 8°-10°C with wind 2 mph. The stumps were inspected (5 each of 4 rep) on Oct. 30 for chip cocoons following removal of bark to the first lateral root. Weevil cocoons were not differentiated as to species.

Taxonomic review of immature dung beetles of the subfamily Scarabaeinae (Coleoptera: Scarabaeidae)

AbstractDiscussion of the taxonomy of scarabaeine larvae includes: (i) a redescription of the subfamily Scarabaeinae based upon larval characters, (ii) descriptions of known genera based upon larvae, and (iii) a key to known genera. Twenty‐five genera representing each of the six currently recognized tribes and most subtribes are considered: Onthophagus, Liatongus, Oniticellus, Onitis, Bubas, Dichotomius, Ontherus, Ateuchus, Scatimus, Canthidium, Neocanthidium, Copris, Heliocopris, Phanaeus, Coprophanaeus, Sulcophanaeus, Sisyphus, Gymnopleurus, Scarabaeus, Megathopa, Canthon. Deltochilum, Canthochilum, Arachnodes and Eurysternus. Four others are treated briefly: Chironitis, Synapsis, Catharsius, Nesosisyphus. On morphological and other grounds, Scatimus and Heliocopris are removed from the subtribe Coprina and reassigned to Dichotomiina. There is little about the variation among larvae studied which supports or weakens the current tribal classification based upon adults as there emerge no combinations of larval characters which satisfactorily define generic groupings. Discussion of scarabaeine pupae is limited to description of pupal support projections of known genera and to definition of the support system characteristic of the subfamily, which is functionally related to nesting behaviour culminating in metamorphosis within a spheroid pupation chamber.

Dispersal Behavior of the Larval Tenebrionid Beetle Zophobas rugipes

In the laboratory, crowding inhibits pupation of larvae of Zophobas rugipes (Coleoptera: Tenebrionidae). Pupation-ready larvae must disperse away from high-density populations in order to find an undisturbed pupation site. In the laboratory, the pupation chamber is defended against intruding larvae, and the success of occupants in preventing intrusion increases with isolation up to 96 h. Thereafter the larvae begin to enter the pharate pupal stage. Over a challenge period of 5-10 h occupant success declines to a plateau but remains above the randomly expected value for 24 h, provided the occupants have been isolated at least 12 h. Dispersal and single occupancy of chambers are due to fighting between occupant and challenger. The major components of the behavior are "shoveling" with the head, opening mandibles, biting the opponent, and violent side-to-side thrashing of the body. All these components increase rapidly during the first 24 h of isolation. Among mature larvae, success in chamber defense is not affected by relative weight (650-750 mg vs. 850-950 mg) or relative age (11-12 mo vs. 14-15 mo). Success is decreased but still significantly nonrandom if occupants are removed from chambers and forced to redisperse along with the challengers. Success is greatly increased if larvae are selected for success in a prior experiment. The ability to defend a pupal chamber successfully thus appears to be an intrinsic property of the larvae. Immobilized larvae are unable to prevent intrusion into their chambers, indicating that single occupancy results from active defense. Pharate pupae and pupae have a limited capacity to exclude intruders from their chambers. Immobilized larvae are subject to heavy cannibalism by active larvae.

CarduusThistle Seed Destruction byRhinocyllus conicus

The impact of a weevil(Rhinocyllus conicusFroel.) (Coleoptera: Curculionidae) onCarduusthistles in Virginia was evaluated in terms of seed reduction and viability during 1973 and 1974. Musk thistle(Carduus nutansL.) seed production from terminal and first lateral heads was reduced by 10% in 1973 and 75% in 1974 due to larval feeding ofR. conicus.The greater seed reduction in 1974 was caused by heavy infestation (45% in 1973, 70% in 1974); there was a five-fold increase in the number of weevil pupation chambers per head over the previous year. Total seed production per plant decreased by 35 to 36% in both years despite increased plant vigor due to better growing conditions in 1974. Larval feeding reduced viability of mature musk thistle seeds. Although individual heads of plumeless thistle(Carduus acanthoidesL.) were frequently destroyed by larval feeding, seed production from early heads of this thistle decreased by only 5% in 1973 and 4% in 1974 due to low rates of infestation (9% in 1973, 5% in 1974). Total seed reduction per plant for each of the two years was less than 0.2%. Infested heads of plumeless thistle did not produce sufficient seeds for evaluation of the weevil's impact on seed viability.

Spatial Distribution of Pine Bark Weevils (Coleoptera : Curculionidae) in Bait Logs

The changes in spatial distribution pattern throughout the developmental period of three species of pine bark weevils, Shirahoshizo spp. (including S. rufescens, S. insidiosus and S. pini), Pissodes nitidus and Pissodes obscurus were observed.There were some differences among the species as for the spatial distribution of oviposition sites, that is, random distribution of P. obscurus, contagious distribution of P. nitidus and uniform distribution of Shirahoshizo spp. But, in all cases, most of the eggs were laid in masses and the distribution of young larvae at their peak was aggregative or colonial, originating in the mass oviposition, regardless of the difference of the spatial distribution of oviposition sites. While the population grew up and larvae dispersed from their hatched sites, the tendency for larvae of all the three species to disperse into random or regular distribution was consistently observed. But after the operation of main mortality factors on each population, the degree of aggregation was increased. The final distribution of pupal chambers of Shirahoshizo spp. was uniform and, on the other hand, these of P. nitidus and P. obscurus were contagious or random.

Occurrence and Survival of the Dispersal Forms of Pine Wood Nematode, Bursaphelenchus lignicolus MAMIYA and KIYOHARA : Ecological significance of dormancy in plant parasitic nematodes. V.

The dispersal 3rd-stage larvae (LIIIs) of B. lignicolus began to occur after 3 to 5 months on the fungal mat of Botrytis cinerea without being subcultured and constituted almost 100% of the surviving nematodes after 10 months. However, extended monoxenic culturing of the nematodes brought about a decrease in the survivability under the starvation and consequently decreased the production of the LIIIs. Addition of fatty extracts from larvae and pupae of a cerambycid beetle. Monochamus alternatus, gave rise to an increase in surviving nematodes and in the LIIIs after being left without subculture. The molting of the LIIIs in water to the dispersal 4th-stage larvae (LIVs) was positively correlated to the developmental stages of the beetle at the collection time of worms. However, most of LIIIs, which had been left in the pupal chambers for 20 days after the removal of the insects, molted into the prpagative 4th-stage larvae (L4s), irrespective of the pupation of the insect. LIIIs and LIVs were both still viable after 100 days under starvation. The live LIVs were recovered from dried cadavers of adult beetles after 6 months. The LIIIs seem to be relatively better able to surive under starvation, whilst the LIVs under dryness.

ASSOCIATION OF DENDROCTONUS PONDEROSAE (COLEOPTERA: SCOLYTIDAE) WITH BLUE STAIN FUNGI AND YEASTS DURING BROOD DEVELOPMENT IN LODGEPOLE PINE

AbstractThe physical association between Dendroctonus ponderosae Hopk. and its associated blue stain fungi Ceratocystis montia Rumb. and Europhium clavigerum Robinson and Davidson and the yeasts Pichia pini (Holst) Phaff, Hansenula capsulata Wickerham, and H. holstii Wickerham is described in single broods reared in bolts of lodgepole pine, Pinus contorta Dougl. var. latifolia Engelm. Eggs just prior to hatch and first-instar larvae were always in contact with the microorganisms whereas newly laid eggs, second-, third-, and fourth-instar larvae were not. During pupation, blue stain fungi and yeasts colonized pupal chamber walls. Transfer of these microorganisms to the new generation of insects was ensured when tenerals contacted the microorganisms lining the pupal chamber. Ensured physical contact between these organisms supports the hypothesis of a symbiosis between them.

Radiographic studies of Sitophilus zeamais Mots. in wheat kernels

Ninety-nine wheat kernels infested by Sitophilus zeamais Mots., were radiographed daily, to study development from egg to adult and behavior of the insects within the kernels. Enlarged photographic prints were prepared from these radiographs to facilitate interpretation. Instars were identified by examining prints and by measuring the widths of tunnels on radiographs and also by measuring the widths of the head capsules of the larvae dissected from kernels. On hatching, each larva was observed to increase the width of the tunnel for a few days, then for 1–3 days the width of the tunnel remained static after which it was again widened. There were four periods of tunnel widening. Since there were four corresponding distinct sizes of head capsules for larvae dissected from kernels, we conclude that the four periods of tunnel widening represent the periods of larval growth and that the periods of static tunnel width define the time of moulting. The average widths of tunnels were successively 0·33, 0·55, 0·90 and 1·49 mm. The mean developmental periods for stadia 1–4 at 27°C and 69 ± 3% r.h. were 3·6, 4·7, 4·8 and 5 days, respectively. Average developmental periods for prepupa, pupa and pre-emerged adult stages were 1, 5·3 and 5·3 days. The average length of the developmental cycle from the start of a 3-day oviposition period to emergence of the adult was 36·3 days. Of the eggs in dissected kernels, 42, 37 and 21 per cent were deposited in endosperm, germ perimeter, and germ center of the kernels, respectively. Of 26 emerged adults, 6 prepared the pupal chamber in one side of the kernel; 8 diagonally across the crease; and 12 parallel to the crease but occupying portions of both kernel halves. Data obtained from these studies are compared with data from previous radiographic studies of Sitophilus oryzae (L.) and S. granarius (L.).

Developmental Activities and Behavior of the Rice Weevil Inside Wheat Kernels12

Fifty-five wheat kernels infested by Sitophilus oryzae (L.) were X-rayed daily to study egg-to-adult development and behavior within the kernels. Enlarged photographic prints (2530) prepared from the radiographs were examined to determine larval instars. Larval-tunnel widths in the daily radiographs were measured, as were head-capsule widths of other larvae from dissected kernels. Four increases in tunnel width occurred, each followed by 1–4 days of static tunnel width (assumed to be time of molting). Four corresponding increases in width of the larval head capsule were observed confirming results obtained by radiographing. The mean tunnel widths for the 4 instars were 0.31, 0.51, 0.83, and 1.34 mm; the means for stadia 1 through 4 were 3.9, 5.4, 4.7, and 5.1 days, respectively. Prepupa, pupa, and pre-emerged adult stages averaged 1, 5.2, and 4.6 days, respectively. The mean life cycle (including 4 days for oviposition) was 37 days. Of 23 adults which developed, 12 had pupal chambers on 1 side of the kernel, with most or all tunneling on that side, 7 constructed pupal chambers parallel to the crease but occupied portions of both kernel halves, and 4 located pupal chambers diagonally across the crease.

Bionomics of Agrilus acutus (Thnb.) (Col., Buprestidae) on mesta (Hibiscus cannabinus) in India

An account is given of the life-history of Agrilus acutus (Thnb.) (Buprestidae), a pest of ‘mesta’ (Hibiscus cannabinus) in india. The eggs are ovate and scale like, and are laid singly on the stem, usually near a leaf scar, and when kept at 31°C. and 73 per cent. relative humidity hatched on average in 12.4 days. The larva bores through the lower surface of the egg directly into the stem and feeds under the bark forming a sprial tunnel. A raised weal develops on the surface of the stem overlying the tunnel. Before each moult, the larva bores into the wood and makes a vertical chamber in which moulting occurs. There are normally three moults in the active feeding stages, but exceptionally four, and a prepupal moult. The rate of tunnelling is at first about 56 mm. per day and later eaches about 107 mm. The larval stage lests 26 days. The fully grown larva is 21 mm. long and bores into the wood to pupate, making a pupal chamber 11 mm. long into which it fits itself by adopting an asymmetrical U-shaped posture. After a prepupal stage of 2.5 days it pupates. The pupal period occupies about 11.7 days and a further seven days are spent by the adult in the pupal chamber. The adult female mates within a day of emergence from the stem. but does not oviposit until at least seven days have elapsed.

Notes on the Biology of Trupanea actinobola (Diptera: Tephritidae)

The immature stages of Trupanea actinobola (Loew), a seed-feeding tephritid, infest the unopened and fully developed flower heads of the daisy fleabane, Erigeron strigosus Muhl. One hundred seventeen unopened flower buds and fully opened flower heads contained 140 pupae and 134 larvae. From 2 to 12 pupae may occupy a pupal chamber in a seed head. Dead seeds or eaten achenes form the pupal chamber around the pupae. Two hymenopterous parasites, Heteroschema punctata (Ashmead) and Colotrechnus ignotus Burks, family Pteromalidae, were reared from the immature stages of T. actinobola. The study was conducted during April and May 1967.

THE BIOLOGY OF THE FIR TREE BORER, SEMANOTUS LITIGIOSUS (COLEOPTERA: CERAMBYCIDAE), IN CALIFORNIA

AbstractThe fir tree borer is found in the coniferous forest belt of North America. The insect can cause serious degrade in lumber manufactured from windthrown white fir. Adults attack host trees in early spring, laying eggs in bark crevices. The incubation period is 10–30 days, depending on temperatures. The larvae excavate winding galleries in the phloem, deeply etching the sapwood, until midsummer when they enter the sapwood. Damage is caused by the larvae boring up to 3 in. into the wood to construct pupal chambers. Pupation lasts 2–4 weeks in fall; callow adults are formed by September and overwinter in the pupal chambers. Emergence occurs the following March or April.Three principal natural enemies were found: two predators, woodpeckers and an ostomid beetle, and a braconid parasite. Population fluctuations hinged on availability of host material and pressure from natural enemies.

Insektenschäden an Souvenirs aus fernen Ländern

There is reported on insects imported to Hamburg in souvenirs and on insect damages on souvenirs from subtropical and tropical countries:Lyctus brunneus (Steph.) in a North-African stringed instrument, pupal chambers ofDermestes maculatus De Geer andfrischii Kugel. in Indian teatable attacked byLyctus sp., bonboo insects especiallyChlorophorus annularis (F.),Niphonoclea furcata (Bates), andDinoderus minutus (F.),Dinoderus brevis Horn in boxes for Japanese okimono-figures,Bostrychoplites cornutus (0l.) in Southwest-African native carved work and drum,Stegobium paniceum (L.) in a leather cushion,Ceratophaga vastella (Zell.) on Angolan hunting trophy, gnawing at goats skin of native drums from Mombassa by young larves ofD. maculatus, damages on Indian tea table by termites, andPachymerus nucleorum (F.) in a Brasilian palmseed-neckchain. The ability to acclimatization of these insects is discused.

Life of Acrobasis rubrifasciella (Lepidoptera: Phycitidae), Its Main Parasite, Agathis calcarata (Hymenoptera: Braconidae), and Three Hyperparasites (Chalcidoidea)

In northeastern Minnesota, the young caterpillar of Acrobasis rubrifasciella (Packard) resumes life in May in the wintered leaf-buds of Alnus . As it grows, mostly in June, it constructs a silken growth tube with an external layer of its fecal pellets, from which shelter it feeds until full-grown. As pupation approaches, it enlarges the end portion of the tube to form a pupal chamber that eventually is bulbous and sealed, separated from the tube by a plug, but with an escape hatch left near the base of the chamber for emergence of the moth. From 1 to 9 caterpillars, each in its own tube, may occur in a single nest, obscured in plant parts bound with gray silk. The pupal and adult stages appeared from June 22 to August 9; apparently the small larvae overwinter. Four instars of Agathis calcarata (Cresson) are described. The first instar was found in host larvae from mid-May to July. Diapause usually ends when the host seals its pupal chamber preparatory to transformation, and the second to fourth instars of Agathis develop in a few days, destroying the host before it can pupate. A cellophane-like cocoon is spun in the host chamber, and the red-and-black adult emerges about 15 days later, through the hatch prepared by the caterpillar. Although actual parasitization and the egg were not observed, the first-instar Agathis apparently winters in first- or, possibly, second-instar caterpillars. Both Acrobasis and Agathis are univoltine. The cocoon phase of this Agathis is subject to attack by 3 chalcid hyperparasites, Perilampus tristis Mayr, Habrocytus sp., and Eupelmella vesicularis (Retzius).

Colobothea distincta (Coleoptera: Cerambycidae) on Cacao: Notes on Its Morphology and Biology1

Females of Colobothea distincta Pascoe lay from 14 to 24 eggs over a 2-day oviposition period, depositing them in groups in the phloem in branches of dying cacao trees. Eggs hatch in 8–12 days. Larvae in early instars feed only in the inner bark, but those in the last instar may feed also upon wood fibers to some extent. The larval stadia require about 6 weeks; 5–9 days are spent in preparation of the pupal chamber in transformation to the pupa; adults emerge in 10–16 days after pupation, and disperse to trees other than the one in which they developed. Adult males lived 19–56 days; females, 44–63 days; both sexes were observed feeding only on the bark of dying cacao trees. Measurements of adults showed no significant differences between collections made at 3 localities in Costa Rica. The ratio of antennal length to body length was strikingly greater in males than in females, as also was the length of the front legs. Because the trees attacked are already dying, this species has little economic importance.

Observations on the biology of some members of the genus Tragocephala (Coleoptera, Lamiidae) associated with Theobroma cacao in West Africa

Members of the genus Tragocephala are widespread as pests of cocoa, and other tree crops, in West and also in East Africa. Those known to be associated with cocoa in West Africa are listed and observations are given on the biology of two of the more important, T. castitnia theobromae Entw. in Ghana and T. castnia cacaoensis Entw. in Nigeria, and a method of laboratory rearing and breeding is described.The egg is laid in an unhardened stem and the oviposition behaviour is complex; the stem is first girdled at a point where it is less than one centimetre in diameter and an oviposition slit excavated above the girdle. The ovipositor is inserted into this slit and the egg is concealed inside the stem; the adult finally closes the oviposition slit with her mandibles.The egg hatches after 11 days and the young larva bores upwards in the dead wood above the girdle. This phase appears obligatory and is followed by one in which the larva bores down into the living stem below the girdle. The mean larval period of T. castnia theobromae in the laboratory was 143 days (range, 70–228 days).A pupal chamber is made by severing the stem beyond about 10 cm. above the end of the gallery and filling the aperture with shreds of wood. The pupal period, in the last half of which adult coloration begins to show, is about 20 days for T. castnia theobromae and 23 days for T. castnia cacaocnsis.Laboratory evidence suggests that there is a post-pupal resting phase in the pupal chamber followed by a free-living non-feeding period; in T. castnia cacaocnsis these lasted on average 6·5 and 4·2 days, respectively, and were followed by intensive feeding on green unhardened stems. The length of life of caged adults varied greatly but the mean was 57·0 and 55·5 days for males and females, respectively, of T. castnia theobromae and 32·0 and 28·5 days for T. castnia cacaoensis. The least preoviposition period noted for T. castnia theobromae was 20 days and previously unmated males and females of this subspecies were still fertile up to at least 76 and 162 days, respectively. Mating normally initiated the bark-ringing behaviour of females and the maximum number of eggs laid by a female of T. castnia theobromae was 146. Considering only individuals that laid 25 or more eggs, an oviposition rate (number of eggs laid per day between first and last oviposition) of 0·51 was recorded for this subspecies. Host plants alternative to cocoa are listed for T. castnia theobromae and T, castnia cacaoensis.The oviposition activity of T. castnia theobromae was least in June, July, August, December and January, whilst for T. castnia cacaoensis very few eggs were laid in the main dry season (November to the following February).The eggs of T. nobilis (F.), T. castnia theobromae and T. castnia cacaoensis, and of another species in the Congo Eepublic, are attacked by the Encyrtid Aprostocetus lamiicidus Kerrich, which in Nigeria appears to undergo a larval diapause in the dry season. Whilst only 5·5 per cent, of eggs were attacked in Ghana, over 50·0 per cent, were attacked in Nigeria. There was an average of 11·7 individuals per egg and the ratio of males to females was 1:2·7.The Tachinid Billaea vanemdeni Fennah was parasitic on larvae of T. nobilis and T. castnia theobromae in Ghana, where its larval stage was in the region of 197 days and its pupal stage 23 days. Incidence of attack was highest from April to July and the two main adult emergence periods were June and September/ October.An Ichneumonid, Nadia sp., is parasitic on either larvae or pupae of T. castnia cacaoensis in Nigeria. Scolytid species incursive in wood dying after being girdled destroy many eggs in Nigeria, where geckoes and ants are thought to be responsible for loss of larvae.Tragocephala can be a locally important pest, especially of seedling cocoa and its numbers may increase considerably if unsuitable chemical control methods are used against other pests of cocoa.The bark-ringing habit in Cerambycidae is discussed.

Biological Studies of a Histiogaster Mite (Acarina: Acaridae) Associated with Pine Reproduction Weevils12

Of more than 40 species of wood-boring beetles checked, only the weevils Hylobius pales (Herbst) and Pachylobius picivorus (Germar) were found to have the mite Histiogaster anops Griffiths associated with them. The mite appears to be a normal inhabitant of the larval tunnels of the weevils, and apparently the adult weevils provide its only means of dispersal. The hypopus, the only stage found on the adult weevil, attaches to the weevil before it cuts through the bark to escape from its pupal chamber. The mites are easily reared with pine phloem or dry yeast as a food source. The feeding stages were consistently attracted more strongly to fresh as opposed to aged pine phloem, but were even more strongly attracted to fresh oak or catalpa phloems. Rearing experiments were successful only on oak and pine phloems. The mite requires an average of 9.6 ± 0.36 days from egg to adult when the hypopial stage does not occur. Average egg production was 101.5 eggs per female; one female produced 317 eggs in 17 egg-laying days. No parthenogenetic reproduction was observed.

THE LIFE HISTORY OF "DIAPREPES ABBREVIATUS" L., AT RIO PIEDRAS, PUERTO RICO

1. The females of Diaprepes abbreviatus L. lay 5,000 or more (or less) eggs in as few as two months, May and June, or in as many as seven months at other times of the year, often living over twice as long as do the males after emergence from the soil. 2. The incubation period of all eggs is seven days. Larvae attain full size in two to four months. A diapause period is absolutely essential before pupation. The pupal period is about two weeks. Fully-formed adults remain within the pupal chamber for a variable period of weeks or months, the length of this period and that of the diapause period of the larva being subject to great variation. 3. The great variation in the duration of the diapause period of the larva and before the emergence of the adult from the pupal cell in the ground permits some individuals to complete their life-cycle (hatch ing of eggs to first egg-cluster laid by female, or to emergence of male from soil) in less than eight months, but for other individuals it may extend for eighteen months (hatching of egg to last egg-cluster laid by female, or to death of male). 4. Deviation from a one-year life-cycle is of tremendous value to Diaprepes abbreviatus L. in enabling its eggs to escape attack by a common parasitic wasp, Tetrastichus haitiensis Gahan, which is most abundant during the late spring, but very scarce during autumn and winter.

On the Genital System of Lyctus brunneus Steph., with a Note on Lyctus linearis Goeze (Coleoptera).

Both sexes in L. brunneus are sexually mature when they have emerged through the wood from their pupal chambers. An external sex-character is described. In the male the reproductive organs consist of two testes of twelve pyriform testicular follicles of unequal size, six arising from each convoluted vas deferens, which terminate in a pair of jointed subcylindrical seminal vesicles. A short tube arises from each seminal vesicle, and forms the ejaculatory duct which empties into the cedeacrus. Partly superimposed over the seminal vesicles and emptying into the short tubes are the paired accessory glands. They are subcylindrical, slightly tapering, and are curved around to underneath the ejaculatory duct. There is a pair of pygidial glands. In the female the reproductive organs consist of two ovaries, each composed of fourteen ovarian tubes with the nutritive cells situated at their apices. The ripe eggs accumulate in a calyx which continues to form the oviduct. The oviducts terminate in a chitinized setsæ-lined paired valve which forms the source of the common oviduct. At this point the voluminous spermatheca arises; it terminates in a tubular spermathecal or accessory gland. The common oviduct disappears into the invaginated double tubular “ovipositor” at a point in the metathorax, where the rectum also enters. In the testicular follicles the spermatozoa are in bundles, in the spermatheca they are in packets or spermatophores. The “ovipositor” has been found to consist of a double tubular prolongation of the ninth abdominal segment, with a reduced tenth segment towards the apex. When extruded the “ovipositor” is approximately the length of the beetle. Situated at the apex of the “ovipositor” are the genitalia with the anus a short distance behind. Arising as an invagination of the eighth sternite and extending into the metathorax is the long, flexible, and strongly-chitinized cloacal stalk, from which arise systems of muscles for exserting and withdrawing the ovipositor. These muscles are found to lie modified intersegmental muscles. Morphologically the gonopore in both sexes was found to arise medianly on the ninth sternite, and the homology of the genitalia appears. In the larva of L. brunneus there are nine pairs of spiracles, one thoracic and eight abdominal; in the adult there are also nine pairs, two thoracic and seven abdominal. The movement which the rectum of the female is subjected to has been observed to be injurious to this organ, in that, lacking any musculatory system for its withdrawal, other than its muscular structure, it was found convoluted inside the “ovipositor” of an eg-laying specimen. This defectiveness must accelerate death.