scholarly journals Life History Phenology and Sediment Size Association of the Dragonfly Cordulegaster dorsalis (Odonata: Cordulegastridae) in an Ephemeral Habitat in Southwestern British Columbia

2006 ◽  
Vol 120 (3) ◽  
pp. 347 ◽  
Author(s):  
Laurie B. Marczak ◽  
John S. Richardson ◽  
Marie-Claire Classen

The life cycle of the dragonfly Cordulegaster dorsalis was studied over one year by systematic sampling of larvae in three intermittent headwater streams in southwestern British Columbia. We determined that larvae normally take three years to reach maturity, emerging throughout July and August. There is limited evidence suggesting a split cohort development, with early emergence after two years. Additionally, we tested whether larval instars were distributed randomly or if they occupied different sediment microhabitats. Smaller animals tend to be associated with smaller grained organic sediments, although there was high variation between the streams.

1973 ◽  
Vol 105 (4) ◽  
pp. 605-612 ◽  
Author(s):  
David Evans

AbstractErannis vancouverensis Hulst occurs from northern British Columbia to central California, and has been occasionally reported at infestation levels. The larvae feed on young leaves of several species of deciduous trees; winter is passed in the egg or sometimes in the pupal stage; adults emerge during late autumn or occasionally during winter or early spring; females are wingless. The life stages, including larval instars, are described here in detail. Virus disease and parasitism by tachinid flies help control the species.


1967 ◽  
Vol 45 (4) ◽  
pp. 397-405 ◽  
Author(s):  
S. Tyrell Smith

The habitat, diet, life history, and reproductive cycle of Retusa obtusa were investigated over a period of [Formula: see text] years in a population found in the Inner Harbour at Barry, Glamorgan, U.K. A technique was devised for extracting Retusa from the mud of this area. R. obtusa occurs in the topmost 3.5 cm of fine mud covering Barry harbor, which is immersed by the sea for only a short time at each high tide. The principal prey was found to be Hydrobia ulvae.The life cycle was found to be annual, the adults dying in spring, following the natural breeding season. Occasionally, a short extra breeding period occurs in the fall. The life span in no case greatly exceeded one year. Retusa is a protandrous hermaphrodite, and copulates in the fall. The eggs mature through the late fall and the winter, a few at a time, until oviposition occurs in the spring. The average number of eggs produced per individual was 33, deposited in 1–4 egg batches. Development is direct.


1998 ◽  
Vol 130 (4) ◽  
pp. 387-397 ◽  
Author(s):  
David W. Langor ◽  
Daryl J.M. Williams

AbstractThe seasonal life history and mortality of the lodgepole terminal weevil, Pissodes terminalis Hopping (Coleoptera: Curculionidae), were investigated in young lodgepole pine, Pinus contorta Douglas var. latifolia Engelmann (Pinaceae), at three sites in west-central Alberta. Flight was monitored with traps. Development and mortality of all stages were investigated by dissecting infested leaders biweekly from late spring to early fall. Two years were required for P. terminalis to complete its life cycle, and generations overlapped. Overwintered adults emerged from the duff and commenced flight in late May, with a peak in mid-June. Eggs were present from mid-June to late July. There were four larval instars. The first two instars fed only in the phloem. Third and fourth larval instars eventually entered the pith to continue feeding, overwinter, and complete development the following spring. The new generation of adults emerged between mid-July and early August, fed on new shoots for several weeks, and overwintered in the duff. Adults have an obligatory diapause and did not reproduce until after winter. Fourth larval instars suffered the highest mortality. The major attributable cause of mortality was resinosis among eggs and young larvae and cold temperatures during the winter among mature larvae. Pathogens caused little mortality. Six species of parasitoids were collected.


Holzforschung ◽  
2002 ◽  
Vol 56 (4) ◽  
pp. 335-359 ◽  
Author(s):  
P. Oevering ◽  
A.J. Pitman

Summary Pselactus spadix attack of marine timbers was characterised by circular emergence holes 1.48±0.05 mm in diameter and adult tunnels (1.49±0.34 mm) breaking through the wood surface. Larval tunnels measured 0.407–1.892 mm in diameter, initiated from adult tunnels and increased in diameter away from the adult tunnel terminating in frass free pupal chambers (1.6±0.3 mm × 3.5±0.7 mm). Observations of larval tunnel locations indicated oviposition occurred inside the adult tunnels. P. spadix life history was investigated in Scots pine (Pinus sylvestris) heartwood at 22±2 °C and 99±1% r.h. Mean adult longevity was 11.5±6.5 months, with mean post-mating longevity for males (11.7±2.9 months) significantly longer than for females (6.3±1.1 months). Adults of at least 2–3 months old were found mating in galleries, which, with observations of the larval tunnel pattern, indicated P. spadix can complete its life cycle without emerging from wood. Five larval instars were identified by measurement of 1722 head capsule widths and application of Dyar's law. Mean development time from 2nd instar to adult emergence was 70.5±6.9 weeks and pupation took 14.6±5.8 days. Development from 2nd instar to reproductive adult took between 17–20 months, with life cycle approximating 24 months at 22±2 °C and 99±1%


1990 ◽  
Vol 2 (1) ◽  
pp. 43-52 ◽  
Author(s):  
Peter Ward ◽  
Angus Atkinson ◽  
Julie M. Peck ◽  
Andrew G. Wood

Euphausiid life histories and distribution in the vicinity of South Georgia were studied from a series of samples taken in April 1980, November–December 1981, and July–August 1983. Size frequency data indicated a two-year life cycle for Euphausia frigida and the possibility of a three-year cycle for E. triacantha. The genus Thysanoessa was represented by a mixture of T. macrura and the dominant T. vicina. A one-year life cycle is proposed for the latter but that of the former is unknown. Spawning in E. frigida and to a lesser extent Thysanoessa spp. commenced as early as July and euphausiid calyptopes were a feature of the plankton for much of the year. E. superba eggs were found in low abundance over the shelf to the north of the island, but no hatched larvae were found. Behaviour patterns such as diurnal and seasonal migration partially confounded attempts to relate euphausiid distribution to environmental features. However calyptopes of most species, were generally more abundant in oceanic water deeper than 500 m and there was limited evidence that in August, E. frigida had commenced spawning in the colder part of the survey area.


1928 ◽  
Vol 19 (1) ◽  
pp. 67-77 ◽  
Author(s):  
R. N. Chrystal ◽  
J. G. Myers

Rhyssa persuasoria and Ibalia leucospoides, both parasitic on Sirex cyaneus, have been studied at Oxford.Rhyssa lays its eggs in the burrow of and near to the almost or quite full-fed host larva or the pupa, by piercing the solid wood with itsovipositor. Feeding is entirely ectoparasitic and takes only a few weeks, during which the host larva may burrow a little further. The winter is passed by Rhyssa as a resting larva. Pupation takes place in the spring, and the whole life-cycle normally occupies one year.Ibalia oviposits in the young larva just before ormore rarely just after hatching, utilising the oviposition-bores of the Sirex for this purpose. The first-stage larva is elongate, with sickle-shaped mandibles, and larval feeding seems wholly endoparasitic. Sirex larvae parasitised by Ibalia confine their boring largely to the outer portions of the trunk, and usually make their final cell just under and approximately parallel to the surface. The life-cycle of Ibalia requires at least two years.Owing to the very different instars which they attack, there seems no risk of superparasitism of Ibalia by Rhyssa or vice versa, and it is therefore suggested that both species be introduced into New Zealand as a measure against Sirex juvencus, which is there very destructive to plantations of Pinus radiata.


1966 ◽  
Vol 98 (7) ◽  
pp. 693-699 ◽  
Author(s):  
L. Daviault ◽  
R. Ducharme

AbstractEpinotia nanana (Tr.) has become increasingly important in recent years in Quebec as it has caused severe defoliation of ornamental spruce trees in the Berthierville area, Quebec. The insect has a one-year life cycle and overwinters in the larval stage, mainly in the fifth instar, in a mined needle. Damage is most noticeable in the spring. Fairly heavy mortality, probably due to unfavourable climatic conditions, occurs among overwintering larvae. The amount of control exerted by parasites is always low.


1958 ◽  
Vol 90 (2) ◽  
pp. 125-127 ◽  
Author(s):  
David Evans

A considerable amount of literature has been published on the genus Pseudohazis and its species but there is only one brief mention of the possibility of a two-year life cycle (Dyar 1904). Several rearings of P. eglanterina form normalis Dyar, completed by the author, have provided conclusive evidence that a two-year cycle is the usual life history pattern in southwestern British Columbia. One such rearing is herein described. This two-year cycle, the first winter in the egg stage and the second winter in the pupal stage, is not in phase as mature larvae and adult moths may be found in the same area at the same time. Detailed descriptions of larval and adult stages are in Dyar 1894 and Packard 1912. Acknowledgment is due to Dr. E. G. Munroe, Unit of Systematic Entomology, Ottawa, for his assistance in reviewing literature and specimen material


1970 ◽  
Vol 102 (2) ◽  
pp. 226-239 ◽  
Author(s):  
R. A. Balogun

AbstractAn investigation of the life-history and habits of Ips cembrae (Heer) has been made at the Ord wood, Cawdor Estate in Nairnshire. The species is polygamous and has a 1-year life cycle with two broods a year. The first broods result from eggs laid in May and June, producing teneral adults in August and September, and the second arise from egg-laying in late September and early October; these second broods generally overwinter under bark in the larval and pupal stages, and the adults emerge the following spring. There are three larval instars before pupation. Maturation feeding of the young beetles and regeneration feeding of the old ones take place either under the bark where broods have developed, or by attacking fresh host trees.


1936 ◽  
Vol 2 (2) ◽  
pp. 209-221 ◽  
Author(s):  
J. G. Rempel

In lakes of Saskatchewan adults emerge in late May and early June. Eggs, deposited over lake surface, sink to bottom. Larvae in soft bottom ooze (10–20 m. depth) grow rapidly in late summer, but little during rest of year. Four larval instars and two-year life-cycle. Larva and pupa described and additions made to Staeger's description of adult.


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