Hatch In Spring Research Articles

Bivoltinism inCoenagrion mercuriale(Zygoptera: Odonata) in the Southern Margin of Its Distribution Range: Emergence Pattern and Larval Growth

Voltinism is an important life history trait that varies with the environment. In temperate zones, insect populations take a substantially longer time to reach the adult stage in the northern compared to the southern regions. In this study, emergence pattern and larval growth of the threatened zygopteran (Odonata) Coenagrion mercuriale were investigated in a population located in the southern limit of its distribution range in order to determine its life history strategies in a hot climate and compare them to those displayed in northern populations. There was no apparent winter diapause. The species produced two generations in a year, with the first generation emerging in mid spring and the second in late summer. The emergence pattern of the first generation was typical of a summer species and lasted 48 days. All larvae emerged by the end of May. Due to some environmental perturbations, the emergence pattern of the second generation was not surveyed, but there was evidence that the emergence season was short (21 days). Larval structure prior to the second emergence of the year showed that only 25%of the population was in the final instar, which explains the shorter emergence season.We assume that the first eggs laid in the spring hatch and grow rapidly to reach the final instar in late summer as a consequence of higher temperatures and potential high food availability. There was a significant seasonal decline in body size in both males and females. The second generation had a significantly smaller body size, presumably due to the short growth season and/or higher growth rate.

Sculpin Predation on Lake Trout Eggs in Interstices: Skull Compression as a Novel Foraging Mechanism

Lake Trout (Salvelinus namaycush) spawn in fall and hatch in spring; to protect their eggs over the winter they spawn on rocky reefs, where the eggs settle deeply into interstices. Uptake of water swells the eggs, further protecting them by lodging in crevices. Freshwater sculpin (Cottidae), the primary predator of salmonid eggs, are small, benthic fishes with malleable bodies and large heads. To acquire the lipid-rich resource contained in eggs, sculpin must penetrate deeply into interstices, and have a method to extract lodged eggs. We placed Slimy Sculpin (Cottus cognatus) into a tunnel containing a sequence of funnels with progressively smaller openings to determine the smallest hole they could enter. Forty-three of 138 Slimy Sculpin (31%) moved through openings up to 19.7% smaller than the maximum width of their head, indicating that they compressed their skull to move through the opening. We examined egg acquisition behavior by placing Lake Trout eggs into holes drilled in a Plexiglass plate. Holes ...

Oviposition on a Shrubby Dicot byOchlodes sylvanoides(Boisduval)(Hesperiidae)

G ENERAL N OTES Journal of the Lepidopterists’ Society OVIPOSITION ON A SHRUBBY DICOT BY OCHLODES SYLVANOIDES (BOISDUVAL)(HESPERIIDAE) Additional key words: Ceanothus cuneatus, Buckbrush, Rhamnaceae, oviposition “mistake ” Most butterflies oviposit on their host plants; thus the first-instar larva does not need to forage actively. Some species that diapause as eggs avoid laying on plant parts that will senesce during the dormant period, and may instead lay on the ground or on litter near the growing point of the emergent host (Fordyce and Nice 2003). MacNeill (1964) described the seemingly anomalous oviposition behavior of the skipper Hesperia lindseyi (Holland) in Marin County, coastal northern California: eggs are laid on lichens on fence posts and trees and the larvae, which develop inside the shell but diapause, hatch in spring and drop to the ground to forage. Scott (1986) reports that eggs are laid “haphazardly” at one site and on annual lupine (Fabaceae) at another, localities not specified. I have seen H. lindseyi oviposit on apparently random dry litter at the soil surface in Colusa County, California. Scott also reports (echoing earlier anecdotes) that another skipper, Polites sabuleti (Boisduval), lays “on the host, on nearby dicotyledons, horsetail plants, soil, etc. (and on a sedge…which larvae refuse).” Different subspecies of P. sabuleti have very different life-cycles and may be uni-,bi-, or multivoltine; Scott does not differentiate among them in the oviposition records at the cited location. On September 15, 2013 I saw a female Ochlodes sylvanoides (Boisduval) “disappear” into a clump of Buckbrush, Ceanothus cuneatus Nutt. (Rhamnaceae) on a serpentine “barren” at 1300m near the town of Washington, Nevada County, California in the foothills of the Sierra Nevada. Curious about what she might be doing, I observed her closely. Over a ten-minute period I saw her lay six eggs individually on twigs in the interior of this densely-branched shrub. She then flew to a nearby clump of Ericameria (Asteraceae) and began nectaring. This species is univoltine in late summer- autumn at this site. There were dry bunchgrasses of several species growing less than a meter from the shrub. All three of the skippers cited are presumed to feed on grasses (Poaceae) but as usual for grass-feeding butterflies, confirmed host records in the wild are rare. Supposedly, P. sabuleti overwinters as a part-grown larva and O. sylvanoides as a first-instar larva (both from scott, 1992). If so, these records of strange oviposition substrates may be unrelated to winter egg dormancy. They could constitute an adaptation to “hide” the eggs from parasitoids that might key in on the larval host plant. In any case, there is a suggestion that grass- feeding skippers may frequently oviposit on non-host substrates, and this should serve as a warning to not take such oviposition “mistakes” as indicating actual or potential larval feeding without further study. L ITERATURE C ITED F ORDYCE , J.A. & C.C.N ICE . 2003. Variation in butterfly egg adhesion: adaptation to local host plant senescence characteristics? Ecol. Letters 6: 23–27. M ACNEILL , C.D. 1964. The skippers of the genus Hesperia in western North America (Lepidoptera: Hesperiidae). University of Cali- fornia publications in Entomology, vol.35. UC Press, Berkeley, CA. S COTT , J.A. 1986. The Butterflies of North America. Stanford Univer- sity Press, Stanford, CA. ———. 1992. Hostplant records for butterflies and skippers (mostly from Colorado) 1959–1992, with new life histories and notes on oviposition, immatures, and ecology. Papilio (n.s.) 6: 1–185 . A RTHUR M. S HAPIRO , Center for Population Biology, University of California, Davis, CA 95616. amshapiro@ucdavis.edu Submitted for publication 17 September 2013; revised and accepted 18 October 2013.

Factors Influencing Habitat Shifts of Age‐0 Yellow Perch in Southwestern Lake Michigan

AbstractYellow perch Perca flavescens exhibit a consistent early life history across most lakes, with hatching in spring followed by a brief pelagic phase that ends with an ontogenetic shift to benthic habitat. This shift occurs with consistent timing and at consistent sizes in most freshwater systems. In Lake Michigan, however, the pelagic phase is prolonged and age‐0 yellow perch undergo the transition to benthic habitat at variable sizes, the reasons for which are unknown. We investigated whether prey resources, diet preferences, and physical environment affected the habitat shift of pelagic, age‐0 yellow perch. The shift to nearshore benthic habitat between 1998 and 2005 was strongly correlated with the occurrence of onshore wind events, a surrogate for transport by onshore currents. The timing of this habitat shift was not strongly related to prey resources. Abiotic factors structured the habitat shifts of age‐0 yellow perch in Lake Michigan, a pattern atypical of freshwater systems but consistent with the patterns seen in marine systems.

Introduction, Scenarios for Establishment and Seasonal Activity of Aedes albopictus in The Netherlands

The Asian tiger mosquito Aedes albopictus was detected for the first time in the Netherlands in the summer of 2005. Aedes albopictus is a competent vector of several human viral diseases, and therefore the recent appearance of the vector is a concern to local public health authorities. In 2006 and 2007, the mosquito was found repeatedly and regularly at Lucky bamboo import companies. To assess whether imported Ae. albopictus could establish to produce subsequent generations in the following years or whether the winter conditions in the Netherlands would prove too cold to allow overwintering of diapausing eggs, predictions were made using a Geographic Information Systems (GIS) model based on January average temperature and the annual precipitation recorded in 2006. Seasonal activity of overwintering Ae. albopictus was estimated for temperate strains based on the weekly average temperature and weekly photoperiod using spring egg hatching thresholds of 10.5 degrees C and 11.25 hours, and egg diapause and adult survival thresholds of 9.5 degrees C and 13.5 hours. The analyses indicate that the climate conditions in the Netherlands over the past 10 years were favorable to allow overwintering of diapausing eggs of temperate strains of Ae. albopictus, particularly in the western coastal region. This region was also the area where adult Ae. albopictus were intercepted inside and surrounding plant glasshouses. The estimated number of weeks elapsing between first egg hatching in spring and the production of diapausing eggs in autumn ranged between 17 and 22 weeks in 2006.

Effects of silt and very fine sand dynamics in Atlantic salmon (Salmo salar) redds on embryo hatching success

We conducted a 2-year field experiment examining the survival to hatching of Atlantic salmon (Salmo salar) in relation to the seasonal and spatial variations of silt and very fine sand (SVFS; <0.125 mm) content within a large set of artificial redds at two spawning sites of the Sainte-Marguerite River, Quebec, Canada. Each artificial redd consisted of an infiltration cube (30 cm × 30 cm × 20 cm) buried in a morpho-sedimentological unit resembling a salmon redd. One hundred fertilized Atlantic salmon eggs were inserted in a number of infiltration cubes during redd construction. The results indicate no significant relation between survival to hatching in spring and values of the sand index or total percent fine sediment <2 mm in redds at that time. However, the proportion of SVFS in the redds explained 83% of the variation in embryo survival, with a threshold at approximately 0.2% SVFS, above which survival dropped sharply below 50%. Infiltration of these very fine fractions mostly occurred under ice cover, during the low-flow winter period. However, during the spring flood period, infiltration-flushing patterns varied spatially and reflected spatial differences in local intensity of bed-load transport and fine sediment availability.

Effects of winter temperatures on gypsy moth egg masses in the Great Lakes region of the United States

Accurate prediction of winter survival of gypsy moth ( Lymantria dispar L.) eggs and phenology of egg hatch in spring are strongly dependent on temperature and are critical aspects of gypsy moth management programs. We monitored internal temperatures of egg masses at three heights aboveground level and at the four cardinal aspects on oak tree stems at two different locations in Michigan during the winter seasons of 1997/1998, 1998/1999 and 1999/2000. Effects of aspect were more strongly associated with observed egg mass temperatures than height above the ground surface. Instantaneous differences between egg mass temperatures on sunny days were as high as 30 °C greater on the southern aspect vs. egg mass temperatures on other aspects, resulting in substantial differences in pre-hatch growing degree accumulations for egg masses on a single tree. Egg masses on southern and western aspects, where solar loading and temperatures were greatest, experienced substantial mortality. Mean survival of eggs averaged across the three seasons was less than 25% on southern and western aspects, compared with averages of 53 and 73% on eastern and northern aspects, respectively. Linear regression of mean monthly egg mass–air temperature differences (between north and south aspects) and mean daily solar flux density resulted in slope coefficient estimates of 0.13 and 0.21 °C MJ m −2, and correlation coefficients of 0.81 and 0.82 at the two field locations, respectively. Using a simple egg mass hatch phenological model, such dissimilarities in temperature and growing degree day accumulation resulted in differences in estimated egg hatch dates of up to 25 days. Snow cover moderated egg mass temperature, with extreme seasonal minimum winter temperatures under snow cover as much as 7.1 °C warmer than those without snow cover.

REPRODUCTION OF THE HERMIT CRAB PAGURUS LANUGINOSUS AND COMPARISON OF REPRODUCTIVE TRAITS AMONG SYMPATRIC SPECIES

Abstract Reproductive traits of Pagurus lanuginosus are described and compared with three sympatric, congener species. Female P. lanuginosus mature at about 5 mm shield length, spawn clutches in autumn and spring, and are considered to have two or more clutches per year. Among the four sympatric Pagurus species (P. lanuginosus, P. middendorffii, P. filholi, P. nigrofascia), spawning season, hatch-out season, annual spawning times, maturity size, and incubation period differed. Specific differences in annual spawning times and some related traits may be explained by differences between species in maximizing the fitness component. Species with several clutches each year and a short incubation may segregate settlement timing to reduce intra- and interspecific competition for unpredictably supplied small shells among settling and newly settled crabs and, thus, maximize the number of clutches per annum. Alternatively, species with single annual clutch, early spring hatch out, and long incubation may be selecte...

Reproduction of the Hermit Crab Pagurus Lanuginosus and Comparison of Reproductive Traits among Sympatric Species

Reproductive traits of Pagurus lanuginosus are described and compared with three sympatric, congener species. Female P. lanuginosus mature at about 5 mm shield length, spawn clutches in autumn and spring, and are considered to have two or more clutches per year. Among the four sympatric Pagurus species (P. lanuginosus, P. middendorffii, P. filholi, P. nigrofascia), spawning season, hatch-out season, annual spawning times, maturity size, and incubation period differed. Specific differences in annual spawning times and some related traits may be explained by differences between species in maximizing the fitness component. Species with several clutches each year and a short incubation may segregate settlement timing to reduce intra- and interspecific competition for unpredictably supplied small shells among settling and newly settled crabs and, thus, maximize the number of clutches per annum. Alternatively, species with single annual clutch, early spring hatch out, and long incubation may be selected to maximize larval survival and/or settlement success if early spring is the optimal season for larval settlement success.

Effects of Pulsed Turbidity and Vessel Traffic on Lake Herring Eggs and Larvae

Proposals to extend commercial shipping in the St. Marys River (connecting Lakes Superior and Huron) to include winter months have raised concerns regarding its effect on lake herring ( Coregonus artedi). Because lake herring spawn in fall and their eggs overwinter in the river and hatch in spring, their hatching success could be impacted by early opening of the locks in spring. Our laboratory studies showed that under the range of turbidities expected in the river due to vessel traffic, lake herring eggs hatched and larvae fed adequately. Field incubation studies produced about 75% survival and 70% hatching success of lake herring eggs at two of three study sites. Collections in the river throughout the month following ice-out showed that sufficient plankton of appropriate size were available to ensure growth and survival of larval lake herring. We did not detect any negative impacts on the early life stages of lake herring as a result of sedimentation in the laboratory or field. However, detailing the spawning sites of lake herring and defining the normal survival-to-hatch in these areas are necessary before making accurate predictions of the effects of early season vessel traffic on lake herring hatching success.

Use of Ornamental Lilac and Honeysuckle Phenophases as Indicators of Rangeland Grasshopper Development

Comparisons were made between phenological phase dates of 2 common ornamental shrubs, purple common lilac (Syringa vulgaris L.) and Zabeli honeysuckle (Lonicera krolkowii Stapf, var. Zabelii (Rehd. Rehder)), and rangeland grasshopper (composite of 6 common species) development for 3 years at 9 sites throughout Montana. Results indicated that spring hatch (75% instar 1) occurred about 10 days after the begin bloom phase of purple common lilac. Peak occurrence of grasshoppers for instar 2 coincided, on average, with the end bloom phase of Zabeli honeysuckle, whereas peak instar 3 occurred about 10 days later. On average, peak instar 4 preceded the first red berry phase of Zabeli honeysuckle by about 8 days, and 75% adult stage occurred about 14 days after red berries first appeared. Our results provide rangeland managers and ranchers with a simple method for the improved timing of assessment and control of rangeland grasshoppers.

Population Dynamics and Seasonal Biology of the Alfalfa Weevil (Coleoptera: Curculionidae) on Alfalfa in Louisiana

The biology of the alfalfa weevil, Hypera postica (Gyllenhal), was studied in Louisiana during 1986 to 1988 on alfalfa, Medicago sativa (L.). Post-estivation migration of adults in the fall occurs during late November and early December. Fall oviposition during December and January resulted in 58 to 81% of alfalfa stems with egg clusters. Egg viability of eggs laid in the fall was estimated at 75%. Alfalfa weevil egg clusters contained an average of 10.9 (1986–1987) to 13.3 (1987–1988) eggs per cluster. The position of egg clusters in the alfalfa canopy, relative to the base of the stem, indicated that 95 and 50% of all clusters were below 40 and 18 cm, respectively. An ovipositional preference was found with eggs generally laid between the upper 30% and lower 80% regions of the alfalfa stem. Alfalfa weevil larvae were first detected in February. Egg eclosion in 1987 was highly synchronized as indicated by larval counts increasing from 4 to 90 per sweep between 3 and 10 February. In 1988, larval emergence gradually increased from 4 February (≦10/sweep) to 3 March (60/sweep). Head capsule widths were 0.15, 0.28, 0.42, and 0.55 mm for first, second, third, and fourth instars, respectively. Corresponding body lengths were 1.4, 2.8, 4.6, and 6.6 mm for first, second, third, and fourth instars, respectively. The marked decline of alfalfa weevils in April is presumably indicative of adult migration from alfalfa to summer estivation sites. Degree-day accumulations are used to describe and predict spring hatch of the alfalfa weevil in Louisiana.

Evaluation of Homeowner Spray Products for Gypsy Moth Egg Mass Control, 1982

Abstract The experimental site was a heavily infested ridge in Frederick Co., Md., before egg hatch in spring. The test materials were applied to individual egg masses until runoff using a 1602 trigger-pump bottle, pressurized aerosol can, or a small paint brush. Some materials were applied to groups of individual egg masses 3 weeks, 2 weeks, and 1 week before hatch. Other materials were tested only once, 2 weeks or 1 week before hatch. Each material-formulation was applied to 20 egg masses. Ten egg masses were brought to the lab where larval hatch and survival were recorded. The remaining 10 were evaluated in the field. Most materials tested resulted in lower survival than the controls. Of the products that were tested on three different dates, the S. C. Johnson products performed significantly better when applied 3 or 2 weeks before hatch than 1 week before hatch. Ficam efficacy was not affected by the time interval between application and hatch. Many of the S. C. Johnson products provided excellent control, as did Ficam at 1 lb/100 gal and 0.5 lb/100 gal. Also among the most efficacious materials were the surfactants Exhault 100, Biofilm, Hydrowet, Triton B-1956, Regulaid, a pine oil (Breath o’Pine), and Neem-seed extract (1:1 in 95% EtOH). Laboratory evaluation allowed accurate 48-h survival counts under artificially controlled temperature and humidity. While field analysis made possible the assessment of product efficacy under realistic natural conditions, only rough estimates of actual mortality could be made. All percentages were transformed to arc sine percentage before analysis.

The biology and metabolism ofOrchomene plebs (Hurley 1965) (Amphipoda: Gammaridea) from McMurdo sound, Ross Sea, Antarctic

O. plebs (Hurley 1965) is a dominant bottom species of amphipoda, occuring in the investigated area at 10 to 760 m. Population structure and sex proportions depend upon the depth and the season of the year of sampling. Development of eggs occurs in winter; the young hatch in spring; the number of eggs produced is proportional to the volume of females. A relationship has been established between length and wet/dry body weight ofO. plebs. The species is necrophagus, long enduring without food. At -1.8°C retention of food in the gut may last from several hours to several days. Heart beat frequency oscillates between 40–80 beats/min at -1.8°C and depends on temperature. A temperature near 8°C is lethal. Oxygen consumption ofO. plebs depends on their developmental stage and sex and on trophic conditions. The level of metabolism of starved animals can be half that of fed animals. The greatest differences in oxygen consumption occur at-1.8°C, the ambient temperature. Oxygen consumption as a reaction to higher temperatures is different for starved and fed animals.O. plebs are hypostenothermic organisms; that is, they can adapt to the lowest temperature occuring in the marine environment.

The Life History of Isonychia sicca (Ephemeroptera:Oligoneuriidae) in an Intermittent Stream in North Central Texas12

The life history of Isonychia sicca (Walsh) was determined from samples collected in intermittent Clear Creek, Oct. 1976–June 1978, Denton Co., TX. Fall hatching nymphs formed a small overwintering brood, grew slowly through the winter and emerged in late Apr. A spring brood hatched in Mar. and emerged late May–early June. Adults from overwintering and spring broods supplied eggs which formed a 2nd generation that emerged late June–early July. Emergence began ca. 20 min after sunset and continued for ca. 2 h. The emergence period was continuous, Apr.–July 1977, with both broods and generations overlapping considerably. Average subimaginal fecundity decreased through the emergence period from 4440 to 621 eggs/female, and was positively correlated with abdominal volume. A decrease in body size was noticeable for nymphs, subimagos and imagos. The sex ratio differed for each stage: 1♂:1.6♀, nymphs; 1.4♂:1♀, subimagos; and, 1♂:3.4♀, imagos. Nymphs filter paniculate matter from water using long foreleg hairs as a seine. Isonychia sicca appears to diapause in the egg stage through dry periods. Upon fall rehydration, eggs slowly break diapause differentially through the fall with those breaking early producing the overwintering brood. Eggs breaking diapause in late fall and winter experience cool water temperatures which probably induce quiescence. Hatching begins again in spring. In a permanent stream, eggs continue to hatch through summer and fall until cool winter temperatures probably induce quiescence and resume hatching in spring.

The Life Cycle and Recruitment of the Sand Shrimp, Crangon septemspinosa, in the Mystic River Estuary, Connecticut

Sampling theC. septemspinosa population of the Mystic River Estuary simultaneously in deep water and along the shoreline indicated that this population has two major reproductive periods. Berried females move into the estuary in early spring and late autumn to hatch their eggs. Two-and three-year-old females produce the larvae in the spring and 1.0- to 1.5-year-old females give rise to the larvae in winter. All larvae are carried seaward by the tidal currents and eventually settle as juveniles in the deep water near the mouth of the estuary or on the continental shelf. Juveniles from the spring hatch migrate to the shallow shoreline where they grow, rapidly, 0.15 mg/day. Those that hatch during the late autumn do not migrate shoreward. A model of this life cycle and evidence to support two recruitment mechanisms that involve inshore migration of adults and the offshore drift of the larvae are presented.

The biology of Gammarus (Crustacea, Amphipoda) in the northwestern Atlantic. VII he duration of embryonic development in five species at various temperatures

The duration of embryonic development in Gammarus duebeni, obtusatus, setosus, lawrencianus, and oceanicus al various temperatures was found lo be related to the reproductive cycle. Slowest development at any temperature occurs in G. setosus which breeds in September and whose young hatch in the next spring. G. duebeni, obtusatus, and oceanicus mate in late autumn and their young are hatched in the next spring; they have a faster rale of development. G. lawrencianus has the fastest rate of development at any temperature; it breeds in January and the young hatch in the spring. The rate of development is correlated with the size of egg.

Forecasting the spring hatch of nematodirus battus by the use of soil temperature data.

Forecasting the spring hatch of nematodirus battus by the use of soil temperature data.

Field Studies on the Biology of the Alfalfa Weevil, Hypera postica,1 in Northeast Mississippi2

Eggs, larvae, and adults of Hypera postica (Gyllenhal)(Coleoptera: Curculionidae) were found in alfalfa fields in northeast Mississippi throughout the winter of 1967–68. Larvae increased in numbers during the spring, but were most abundant in late March 1967 and from late March through mid-April in 1968. Larvae were present in small numbers in alfalfa during late summer in 1967. The presence of larvae in alfalfa at this time indicates that oviposition apparently occurred throughout winter and spring, resulting in an overlapping of egg hatch in spring and early summer. No larvae were collected in alfalfa during the period following the 1968 peak, further suggesting only 1 generation of weevils per year in northeast Mississippi. Adult weevils were most abundant during May 1967 and June 1968. Adults apparently moved out of alfalfa to aestivation sites in late May 1967 and June 1968. Weevil movement back to alfalfa apparently began in October in 1967, and increased through January 1968. Weevil return to alfalfa in the fall of 1968 occurred about November. Dissection of females revealed that egg maturation occurred principally during the period from October 1967 through March 1968. Eggs were most abundant in alfalfa stems in January and February.

The Effect of Monthly Hatches on Performance Traits of White Leghorn Pullets

The effects of monthly hatches on various performance traits were studied with pedigreed chickens originated from the same parents throughout a year. The characters analysed in this report are age of sexual maturity, body weight at first egg and at twelve months of age, egg weight at ten months of age, pullet year egg production, and adult viability.It is concluded that the age of sexual maturity depends primarily on changes in daylength occuring during the growing period, and thus should be longest for the June hatch and shortest for the December hatch under natural daylight. The dependency of the character on the day length is best explained by fitting a quardratic equation, y=161-2.05x+0.25x2in which y stands for sexual maturity in days and x for the difference between day length in hours at sexual maturity and hatching dates.Although body weight at sexual maturity shows high correlation with the age of sexual maturity, rather poor ranking correspondence of sire group's records of these two traits suggests that the genetic correlation may differ substantially from the phenotypic association. Body weight at twelve months of age was largest in the May hatch and smallest in the July, the difference being approximately 400 grams. Two measures of body weight were negatively correlated each other.Annual egg poduction starting from first egg was highest for the April hatch and lowest for the September, whereas egg size at ten months of age was largest in the Febuary hatch and smallest in the September. Thus, the Febuary hatch or early spring hatch is more profitable than fall hatches.Egg production pattern, defined as the pattern of average monthly production rate starting from onset of production up to 540 days of age of pullets hatched contemporally, shows distinct features characterized by one or two production peaks with or without a sharp decline occuring during winter season. When birds encounter winter before they go to their production peak, uni-modal production pattern which has only one peak is seen (i. e. June and July), while bi-modal pattern characterized by the winter decline will be observed otherwise (i. e. December through April). Some applications of the results to the techniques of artificial lighting were discussed.Sire by hatch interaction was significant only in age of sexual maturiurity (p _??_ .05) and twelve omnths body weight (p<.01). Genetic correlation of egg production between spring and fall hatches after pooling three months of data was practically none, which suggests ranking of sire groups hatched in spring and fall lucks its consistency. Implications to selection and performance test involving seasonal difference were also discussed.