SOME PHYSICAL REQUIREMENTS FOR OSTRICH EGG INCUBATION

Jarvis, M. J. F., Keffen, R. H. & Jarvis, C. 1985. Some physical requirementsfor Ostrich egg incubation. Ostrich 56: 42–51.

Eggs from wild and domesticated Ostriches Struthio camelus australis were studied to determine temperature and humidity requirements for successful incubation. Wild eggs in Zimbabwe included some collected and incubated artificially, and others that were naturally incubated until just before hatching. Egg-weight losses during incubation were measured. The eggs artificially incubated at 35 °C to 36°C and 40–42% relative humidity, lost nearly the same weight as did eggs in naturally incubated nests. Comparisons were made between the wild eggs and chicks, and those from domesticated hybrid-strain Ostriches in Bophuthatswana. The discussion outlines some of the remaining problems associated with Ostrich egg incubation.     

4. CLIMPSES OF THE NARINA TROGON

Bertram, B. C. R. &; Burger, A. E. 1981. Aspects of incubation in Ostriches. Ostrich 52:36-43.

We studied incubation in domesticated Ostriches Struthio camelus in South Africa and wild Ostriches in Kenya. Although the eggs were large, with relatively high thermal capacities, unattended eggs exposed to the sun reached dangerously high temperatures (40,5°C). Experimental exposure of fresh eggs to the sun for seven days prior to incubation greatly reduced the percentage of embryos which developed, and no embryos survived 15 days of exposure. In the wild. Ostriches frequently shade their eggs in the pre-incubation period to prevent overheating.

During natural incubation, temperatures in the eggs (range 30,8-33,8°C) and of nest-air (31,9-34,6°C) were remarkably constant, despite the daily ambient fluctuations of air temperatures (17,8-38,9°C). Similarly the humidity of the nest-air (39–52%) was lower and less variable than the ambient air (39–72%). Water loss during 42 days of incubation was 11–12% of initial egg weight and, in addition, early laid eggs lost 3–4% during the 2½-3 week pre-incubation period. The water vapour conductivity and the daily water loss of Ostrich eggs were similar to those of other birds, in proportion to epg size, despite the arid environment inhabited by Ostriches. Some of the constraints on the feeding and breeding behaviour of Ostriches imposed by the physical requirements of their eggs are discussed.     

Breeding seasons and laying patterns of the southern African Ostrich Struthio camelus

Wild Zimbabwe Ostriches Struthio camelus were studied during four successive years. Information on breeding seasons and laying patterns was compared with that of domesticated South African hybrid Ostriches in Bophuthatswana. In wild populations laying occurred mainly from July to December or early January, while domesticated birds continued until at least the end of February. Domesticated birds normally laid about 16 eggs in succession, one every second day. There was marked synchronisation of laying and the middle of each successive peak in egg production was about 6 weeks from the preceding peak. Wild birds laid up to eight eggs in any one nest, and normally clutches were contributed by three females, the average combined clutch being 12 or 13 per nest. Circumstantial evidence suggests that individual females may lay in more than one nest during a single laying sequence. Comparisons between rainfall patterns and laying rhythms proved inconclusive.     

ESTIMATING THE MATING BEHAVIOR OF A PAIR OF HYBRIDIZING HELICONIUS SPECIES IN THE WILD

Premating isolation between incipient species is rarely studied in nature, even though mating tests in captivity may give an inaccurate picture of natural hybridization. We studied premating barriers between the warningly colored butterflies Heliconius erato and H. himera (Lepidoptera) in a narrow contact zone in Ecuador, where hybrids are found at low frequency. Eggs obtained from wild-mated females, supplemented with eggs and young larvae collected from the wild, were reared to adulthood. Adult color patterns of these progeny were then used to infer how their parents must have mated. Likelihood was used to estimate both the frequencies of potential parental genotypes from adult phenotypes collected in the wild, and the degree of assortative mating from the inferred parents. The frequencies of parental genotypes varied across the hybrid zone, but our statistical method allowed estimates of hybrid deficit and assortative mating to be integrated across all sites sampled. The best estimate of the frequency of F₁ and backcross hybrid adults in the center of the hybrid zone was 10%, with support limits (7.1%, 13.0%; support limits are asymptotically equivalent to 95% confidence limits). Mating was highly assortative: in the center of the hybrid zone the cross-mating probability between H. erato and H. himera was only 5% (0.3%, 21.4%). Wild hybrids themselves mated with both pure forms, and the probabilities that they mated in any direction were not significantly lower than those among conspecifics. These results are consistent with earlier laboratory studies on mate choice, and suggest that selection against hybrids must be strong to prevent formation of a hybrid swarm. Unfortunately, the wide support limits on mating behavior precluded a measure of the strength of selection from these data alone. Our statistical approach provides a useful general method for estimating mate choice in the wild.     

Dimensions and composition of eggs from captive bustards (Gruiformes: Otididae): houbara (Chlamydotis undulata), rufous‐crested (Eupodotis ruficrista), and kori (Ardeotis kori)

This study sought to increase understanding of the size and composition of eggs from two subspecies of houbara bustard (Chlamydotis undulata macqueenii and C. u. undulata). Eggs from the rufous‐crested bustard (Eupodotis ruficrista) and kori bustard (Ardeotis kori) were also examined for comparison. Infertile eggs were collected from captive birds; egg mass and linear dimensions were recorded, and egg component masses were determined wet and dry. Significant differences were observed in the composition of the eggs from the two houbara subspecies. Despite being smaller in size, eggs from the macqueenii subspecies had a relatively larger yolk (and relatively less albumen) than eggs from the undulata subspecies. The relative composition of the rufous‐crested and kori bustard eggs showed patterns similar to that of the undulata eggs. For the houbara bustards, changes in initial egg mass (IEM) were associated with changes in egg length more than egg breadth, and changes in egg length and breadth appeared to be due more to increases in albumen mass than to increases in yolk mass. Zoo Biol 21:337–346, 2002. © 2002 Wiley‐Liss, Inc.     

Captive breeding for reintroduction: influence of management practices and biological factors on survival of captive kaki (black stilt)

An important component of the restoration strategy for the critically endangered kaki or black stilt (Himantopus novaezelandiae) is captive breeding for release. Since 1981 1,879 eggs were collected from wild and captive pairs, with birds laying up to four clutches. Eggs were incubated artificially and most chicks reared by hand until released as juveniles (about 60 days) or sub‐adults (9–10 months). Because survival in captivity is a significant determinant of the number of birds available for release, we wished to identify sources of variation in mortality to assess potential impacts of management on productivity. Hatchability was 78% for captive‐laid eggs and 91% for wild‐laid eggs. Survival of hatched eggs was 82% by 10 months of age for both wild and captive birds. Most egg mortality occurred early in incubation and around hatching: the timing of mortality was unaffected by whether birds were captive or wild, hybrid or pure kaki, or when eggs were laid. Heavier hatchlings showed higher initial survival, as did chicks from wild parents. Hatchlings from fourth‐laid eggs showed lowest survival, even though hatchling mass tended to increase with hatch order. Survival of chicks subjected to major health interventions was 69% after 4 months. No differences in survival were found between different genders, hybrids and pure kaki, hand‐reared or parent‐reared birds, chicks hatching early or late in the season, different seasons, different‐sized groups of chicks, chicks reared in different brooders, juveniles kept in different aviaries, and chicks from subsequent clutches. Birds subjected to minor health interventions were equally likely to survive as healthy chicks (82%). Survival was high despite aggressive management (quadruple clutching and collecting late in the season). Differences between captive and wild birds suggest further improvements could be made to captive diet. Wide variation in hatchability between parent pairs substantiates the practice of breaking up poorly performing pairs. Zoo Biol 0:1–16, 2005. © 2005 Wiley‐Liss, Inc.     

THE OCCURRENCE OF FLAGELLATED EGGS IN LAMINARIA ANGUSTATA (PHAEOPHYTA,LAMINARIALES)1

Eggs of laminaria angustata Kjellman were shown to have two flagella. Compared with flagella of other phaeophycean swarmers, those of Laminaria eggs have several unique characters such as lack of mastigonemes, widely spaced basal bodies and no flagellar rootlets. The flagella abscise during egg liberation.     

FACTORS AFFECTING THE EGG SIZE OF RED-BILLED GULLS LARUS NOVAEHOLLANDIAE SCOPULINUS

The factors influencing the egg size of the Red-billed Gull Larus novaehollandiae scopulinus were studied at Kaikoura, New Zealand, between 1964 and 1972. In two- and three-egg clutches there was a trend for the eggs to become smaller in the sequence of laying. Length, breadth and volume of eggs of one-, two- and three-egg clutches declined significantly as the season progressed. The size of eggs from single-egg clutches tended to be smaller than eggs from two-egg clutches laid at the same time. There were correlations between the proportions of one-egg and of three-egg clutches being laid at a given period and the mean egg volume of two-egg clutches. When the mean egg volume of two-egg clutches increased there was a corresponding increase in the proportion of two- and three-egg clutches laid. When the mean egg volume of two-egg clutches decreased there was an increase in the proportion of single-egg clutches laid. The egg size of the Red-billed Gull showed no direct correlation with the abundance or availability of food; the largest eggs were produced early in the season when food was in short supply. In spite of an increase in the food supply in the middle of the breeding season, birds laying at this time produced smaller eggs than birds which laid earlier in the season. However, early breeders which relayed at the peak in food abundance on average produced a larger replacement clutch than originals laid early in the season. It is suggested that the birds nesting early in the season are able to produce the largest eggs because they are the most efficient foragers for food, and those which nest later in the season produce smaller eggs, even at peak food abundance, because of their inefficiency or inexperience. Early breeders laying replacement clutches tended to lay larger eggs and larger clutches than birds which are producing their first clutches at the same time. Two-year-old females laid eggs which were significantly shorter than older aged birds while the breadth and volume of the egg increased with the age of the female up to the fifth year. There was a trend for females to lay larger eggs when mated with older rather than younger males. No statistical differences in egg size were detected between females changing or retaining the partner of the previous season. Female body weight and egg volume were positively correlated in females weighing less than 275 g but not for heavier females. It is suggested that the seasonal decline in egg size and clutch size results from a decrease in the availability of food and the ability of the individual to exploit the resource.     

THE BREEDING ECOLOGY OF ROYAL TERNS STERNA (THALASSEUS) MAXIMA MAXIMA

The breeding ecology of the New World race of the Royal Tern Sterna maxima maxima was studied at colonies in Virginia and North Carolina, U.S.A., from 1967 to 1970. Colony sites are quite varied, but isolation, good distance visibility and (especially) freedom from quadruped predators seem important if not essential prerequisites. In Virginia, most adults arrive at the colony site in the last few days of March. Courtship, displaying and copulation take place at, near, and some distance from the colony site. In this the Royal Tern differs from its near relative S. sandvicensis sandvicensis which carries out these activities away from the colony site, presumably as an anti-predator device. Courtship displays are not described, but in their essentials are similar to those of other terns. Copulations continue throughout incubation and gradually disappear when the eggs hatch. No post-copulatory displays are known. Some synchrony of egg-laying is evident, but no “mass laying” occurs, the colony increasing in size steadily over a period of weeks and months. Defaecation on the nest is normal and probably serves to strengthen the nest rim against flooding by high tides. Contrary to published reports, the normal clutch is one; the largest is two, probably often from two different females. All incubating adults examined had two brood patches. Average egg measurements are 63 × 44-5 mm, and average egg weight is 64.3 g. Egg colour varies greatly, and evaluation is difficult. Eggs are probably not cryptically coloured and individual variation, as well as nest-site, are used by returning adults to identify their own eggs. Average maximum nest density is c. 7/m². Sterna sandvicensis acuflavida nests regularly, if not obligatorily, with m. maxima; interactions between the two, and possible benefits accruing to each, are discussed. Unhatched eggs were significantly nearer other nests than were successfully hatched eggs, and possible explanations are given. Incubation lasts about 30–31 days, a week longer than in most terns; both sexes incubate. Broken eggshells are never removed by the adults. Instead, after 2–3 days, the chicks leave the nest permanently to join a creche that roams freely about the immediate vicinity of the colony. Chicks remain in the creche for about 25–30 days, leaving it at fledging, approximately 30 days after hatching. While in the creche, chicks are normally fed only by their parents, who probably recognise them both vocally and visually, using the extensive variation in voice and colour of chicks characteristic of the species. Sandvicensis acuflavida chicks also are highly variable, and join Royal creches, adults of both species attending. Variation also occurs in Royals' juvenal plumage, and seems associated with extended parental care. Feeding adults normally wander up to 40 km from their colony, and this probably facilitates the intercolonial exchange of breeding birds we recorded. They feed inshore, in shallow waters, taking small fish by dives which do not go below the surface. They regularly take small soft-shell crabs in this way, and frequently water-skim like skimmers Rynchops spp., sometimes capturing food while doing so. A relationship between crab capture and water-skimming is established for the first time, and water-skimming in non-feeding contexts is mentioned. Besides the quadruped predators which they normally avoid by fleeing the colony site, Royals have no known predators beyond the egg stage. Eggs, although not chicks, are readily taken by Laughing Gulls. Relationships between the two species are discussed, emphasising their constant association the year round.     

ULTRASTRUCTURAL AND FUNCTIONAL MORPHOLOGY OF EGGSHELLS SUPPORTS THE IDEA THAT DINOSAUR EGGS WERE INCUBATED BURIED IN A SUBSTRATE

Abstract:  The reproductive biology of dinosaurs is of great interest, particularly in light of the many fossil eggs assigned to this group. The ultrastructural characteristics of dinosaur eggshells are examined in order to calculate water vapour conductance, which indicates the nesting environment. Data were mainly derived from the literature but new values are also presented. Allometric analyses were carried out on a variety of shell parameters against predicted egg mass, and comparison was made with allometric equations for bird eggs. Shell thickness was generally larger than seen for extant birds. Total pore number and pores per unit area were similar to values predicted from bird eggs. Total pore area showed an isometric increase with egg mass, parallel to the relationship for birds, but the constant value was an order to magnitude higher than the bird values. Pore radius was unaffected by egg mass. Water vapour conductance showed an allometric increase with egg mass, parallel to the bird values, but for any given egg mass values for dinosaurs were an order of magnitude higher. Mass-specific water vapour conductance was unaffected by egg mass but was an order of magnitude higher than the bird values. Water vapour conductance per pore showed an allometric decrease with egg mass but again the predicted values were an order of magnitude higher than for bird eggs. The ultrastructural characteristics of dinosaur eggshells indicate that the nesting environment had to be saturated with water vapour and that dinosaur eggs had to be fully buried in a substrate. In this sense, therefore, dinosaur eggs resemble more those of modern reptiles than those of birds. As a consequence, maintenance of incubation conditions would have depended on the prevailing environment.     

Differences in development time,mortality and water loss between eggs from laboratory and wild populations ofDermatophagoides pteronyssinus (Trouessart, 1897) (Acari: Pyroglyphidae)

A total of four microcultures of adults ofDermatophagoides pteronyssinus, two each from laboratory and wild populations, were fed on separate diets of house dust and yeast granules. A total of 35 eggs of known age from each of the four microcultures were harvested and incubated at 15°C, 60% RH for 16 h/day and 30°C, 75% RH for 8 h/day to simulate diurnal microclimatic fluctuations in a bed. Eggs from females fed on yeast were larger and underwent more rapid rates of water loss, estimated by measurements of reduction in visible surface area (VSA), than eggs from females fed on house dust. There were no significant differences in mean egg development time between the four microcultures (range 6.0–6.88 days). Mortality of the eggs was as follows: from laboratory females fed on yeast, 31.4%; laboratory females fed on house dust, 11.5%; wild females fed on yeast, 2.9%; wild females fed on house dust, 0%. Thus diet and egg size at oviposition had no effect on mortality. Since the microclimates at which eggs from both populations were oviposited and incubated were identical, it is hypothesized that mortality was higer in eggs from laboratory cultures because the mites had become acclimated to the optimal conditions at which they had been kept and were less able to withstand the diurnal fluctuations in microclimate, similar to those imposed upon wild mites in their natural habitats.     

OBSERVATIONS ON THE SLATY EGRET EGRETTA VINACEIGULA IN NORTHERN NAMIBIA

Hines, C.J.H. 1992. Observations on the Slaty Egret Egretta vinaceigula in northern Namibia. Ostrich 63: 118–122.

The Slaty Egret is an endemic African resident with a limited distribution in Botswana, Zambia and Namibia. Distribution records for Namibia are reviewed and information on movements and habitat preferences is given. Diet and feeding habits are described. Two colonies of Slaty Egrets containing eggs and chicks were found on temporary wetlands in eastern Bushmanland. Nests and eggs are described and egg measurements and weights given. The plumage of immature birds is described as well as the variation in adult plumages. The conservation status of the species is reviewed, and the possible importance of temporary wetlands to the Slaty Egret is discussed.     

6. THE PROBLEM OF NOMENCLATURE

Hockey, P. A. R. 1983. Aspects of the breeding biology of the African Black Oystercatcher. Ostrich 54:26-35. Fifty-five pairs of African Black Oystercatchers Haematopus moquini bred at Marcus Island in 1979–1980. Sixteen pairs laid replacement clutches: the mean interval between loss of the fist clutch and laying of a replacement clutch was 22,2 days. Mean inter-nest distance was 19,4 m. The modal clutch size was 2, with a mean of 1.74. Mean dimensions of 105 eggs were 60,7 × 40,l mm and mean fresh egg mass was 55,s g. There were differences in egg mass and dimensions between eggs in one- and two-egg clutches. Rate of egg loss was high, due mainly to depredation by Kelp Gulls Larus dominicanus promoted by human disturbance. Fledging success was lower at a disturbed site than at undisturbed sites, with highest chick mortality occurring in the first week of life. Mortality of first-year birds of eight days and older was estimated at 48% and 69% in two successive seasons. All juvenile birds dispersed from the natal sites, and were resighted up to 168 km away. Dispersed juveniles were concentrated at the edge of an area of high oystercatcher density.     

Size‐dependent reproductive success of wild zebrafish Danio rerio in the laboratory

Size‐dependent reproductive success of wild zebrafish Danio rerio was studied under controlled conditions in the laboratory to further understand the influence of spawner body size on reproductive output and egg and larval traits. Three different spawner size categories attained by size‐selective harvesting of the F₁‐offspring of wild D. rerio were established and their reproductive performance compared during a 5 day period. As to be expected, large females spawned more frequently and had significantly greater clutch sizes than small females. Contrary to expectations, small females produced larger eggs when measured as egg diameter with similar amounts of yolk compared to eggs spawned by large spawners. Eggs from small fish, however, suffered from higher egg mortality than the eggs of large individuals. Embryos from small‐sized spawners also hatched later than offspring from eggs laid by large females. Larval standard length (L_S)‐at‐hatch did not differ between the size categories, but the offspring of the large fish had significantly larger area‐at‐hatch and greater yolk‐sac volume indicating better condition. Offspring growth rates were generally similar between offspring from all size categories, but they were significantly higher for offspring spawned by small females in terms of L_S between days 60 and 90 post‐fertilization. Despite temporarily higher growth rates among the small fish offspring, the smaller energy reserves at hatching translated into lower condition later in ontogeny. It appeared that the influence of spawner body size on egg and larval traits was relatively pronounced early in development and seemed to remain in terms of condition, but not in growth, after the onset of exogenous feeding. Further studies are needed to explore the mechanisms behind the differences in offspring quality between large‐ and small‐sized spawners by disentangling size‐dependent maternal and paternal effects on reproductive variables in D. rerio.     

Domestication is associated with differential expression of pikeperch egg proteins involved in metabolism,immune response and protein folding

Domestication is a condition in which the breeding, care and feeding of animals are, at least in part, controlled by humans. Information regarding the changes in the protein composition of eggs in response to domestication is very limited. Such data are prerequisite for improvements in the reproduction of domesticated fish. The aim of this study was to examine the impact of domestication on the proteome of pikeperch eggs using two-dimensional differential in-gel electrophoresis. We analysed high-quality eggs from domesticated and wild pikeperch fish to reveal proteins that were presumably only related to the domestication process and not to the quality of eggs. Here, we show that domestication has a profound impact on the protein profile of pikeperch eggs. We identified 66 differentially abundant protein spots, including 27 spots that were more abundant in wild-caught pikeperch eggs and 39 spots that were enriched in eggs collected from domesticated females. Eggs originating from wild-caught females showed higher expression levels of proteins involved in folding, apoptotic process, purine metabolism and immune response, whereas eggs of domesticated females showed higher expression levels of proteins that participated mainly in metabolism. The changes in metabolic proteins in eggs from domesticated females can reflect the adaptation of pikeperch to commercial diets, which have profoundly distinct compositions compared with natural diets. The decrease in the abundance of proteins related to immune response in eggs from the domesticated population suggests that domestication may lead to disturbances in defence mechanisms. In turn, the lower abundance of heat shock proteins in eggs of domesticated fish may indicate their adaptation to stable farming conditions and reduced environmental stressors or their better tolerance of stress from breeding. The proteins identified in this study can increase our knowledge concerning the mechanism of the pikeperch domestication process.     

Egg development time in the Zebra Finch Taeniopygia guttata varies with laying order and clutch size

As female birds are able to lay no more than a single egg each day, in those species producing larger clutches the first laid eggs may get a developmental head‐start over later eggs in the clutch. All other things being equal, the differential pattern of development across the clutch may contribute to hatching asynchrony and subsequent inequity in the competition between brood mates, and ultimately increase variance in the quality and fitness of first‐ and last‐laid offspring. It has been suggested that females might allocate resources differently across the laying sequence to moderate the developmental rate and hatching time of different embryos. We tested this theory in the Zebra Finch Taeniopygia guttata, a common model species for investigating maternal effects in birds. We removed 758 eggs from 160 nests shortly after they were laid and used artificial incubators to control for parental effects and monitor hatching times. Eggs from larger clutches consistently hatched sooner than those from average‐sized clutches, demonstrating that the intrinsic properties of an egg can alter the developmental time of embryos. There were also differences in the development time of eggs across the laying sequence, but these patterns were weaker, inconsistent and unrelated to sequential investment across the laying sequence in a straightforward way. This study indicates that maternal resource allocation to eggs across the laying sequence and across clutch sizes can influence development times and play a potentially important role in determining the competitive dynamics of broods.     

Domestication of tomato has reduced the attraction of herbivore natural enemies to pest‐damaged plants

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Variations in the sizes of gonads,eggs and larvae of the dace,Leuciscus leuciscus

Synopsis Prespawning female dace were examined in 7 successive years; in 6 years mean egg size (mm³) and egg number were inversely related and hence the ovary weights of equivalent-sized females were constant. Fecundity increased logarithmically with fish length, and an index of reproductive effort (ovary weight ÷ length cubed) also increased. The number of eggs per gram of ovarian tissue decreased with fish length; this was because mean egg size (mm³) increased and not because of a change in the proportion of connective tissue in the ovary. But in 1977, both egg number and mean egg size were low, although very high somatic growth had occurred in the previous, very warm, summer of 1976. Eggs from different-sized female dace were artificially fertilized, and incubated at a constant temperature. Dry weights of larvae, egg dry weights, mean egg size and larval starvation times showed linear correlations with each other and with parental (female) lengths. The progeny from the very smallest parent died several days earlier than those from the other parents. Size-related predation rates may be of more consequence than starvation death in natural populations. The optimum position of dace along the continuum between many small eggs and fewer larger eggs may vary at different levels of reproductive effort.     

Evidence for embryo–embryo interactions in controlling hatching time and synchronization in the brown marmorated stink bug,Halyomorpha halys (Hemiptera: Pentatomidae)

The mechanisms controlling egg diapause and circadian rhythms of hatching activity have been extensively studied in insects. However, relatively little attention has been paid to the mechanisms controlling synchronized hatching from an egg mass. In this study, we examined the possible involvement of embryo–embryo interaction in controlling hatching time in Halyomorpha halys (Stål). Eggs tended to hatch earlier as the egg mass size increased. Egg separation and clumping of separated eggs at various times showed that hatching synchrony was largely determined shortly before hatching. However, whether eggs were kept in a mass or separated until several hours before hatching also influenced the hatching time, indicating the presence of embryo–embryo interactions. Eggs derived from different masses and kept in physical contact with one another hatched synchronously if their ages were within approximately 8 h. In this case, both younger and older eggs advanced only in hatching time, in contrast to a case of locusts reported by others. Eggs separated by more than 7 mm hatched as synchronously as those kept in a mass when glued to the same substrate, suggesting an important role of the egg substrate in transmitting the vibrational hatching signals to neighboring sibling eggs to synchronize hatching.     

Counterstrategy to Egg Dumping in a Coreid Bug: Recipient Individuals Discard Eggs from Their Backs

The golden egg bug, Phyllomorpha laciniata Vill. (Heteroptera: Coreidae), is the only terrestrial insect in which females oviposit on the backs of female and male conspecifics. Eggs do not survive unless carried by a bug. Herein, I report laboratory observations that egg-carrying individuals actively brush their backs against the host plant seemingly in an effort to rub off eggs. Egg scraping is more common among individuals carrying many eggs than among those carrying only a few eggs. The most recently received eggs were rubbed off first. Females did not avoid laying eggs on the backs of egg-loaded individuals, nor did bugs carrying several eggs resist oviposition attempts more often than unloaded ones. Some males were likely to have fertilized the eggs they scraped off their backs. Laboratory results of active egg removal correspond with egg loss in the field, suggesting that egg scraping may explain egg loss in nature. The data indicate a cost of egg carrying to an individual and an evolutionary arms race between oviposition and discarding behavior.