Number Of Larval Instars Research Articles

Development and reproductive biology of Dermaptera: a comparative study of thirteen species from eight families

Abstract We examine and describe the embryonic development of 13 species from eight families of Dermaptera, i.e., all families excluding Karschiellidae, Hemimeridae, and Arixeniidae: Diplatys flavicollis (Diplatyidae), Cranopygia sp., Echinosoma sp., and Parapsalis infernalis (Pygidicranidae), Apachyus chartaceus (Apachyidae), Anisolabis maritima and Euborellia pallipes (Anisolabididae), Labidura riparia (Labiduridae), Forficula scudderi and Anechura harmandi (Forficulidae), Paralabella curvicauda (Spongiphoridae), and Proreus simulans and chelisochid gen. sp. (Chelisochidae). We also provide new findings on the reproductive biology of the Pygidicranidae and the postembryonic development of the Apachyidae. Based on information from the present and previous studies, we reconstruct the developmental and reproductive-biological groundplan for Dermaptera and discuss phylogenetic issues related to this order. We confirmed that Dermaptera possesses the embryological features (related to mode of embryonic formation and manner of blastokinesis) that are regarded as autapomorphies of Polyneoptera. Eudermaptera is characterized by the extraordinarily great length of the embryo which attains its maximum length in anatrepsis period, the positioning of its posterior end at the egg’s anterior ventral side, the type of egg tooth, and four larval instars. Anisolabididae, Labiduridae, and Eudermaptera share an elongation ratio of embryos in the anatrepsis period (ERE) of 160% or less and a larval instar number of five or less, whereas Protodermaptera is characterized by an ERE of 210% or more, a ratio of embryonic primordium relative to the egg’s longitudinal circumference (IL) of 40% or less, and a larval instar number of six or more. Notably, the ERE, IL, and larval instar number of Apachyidae are within the ranges observed in Protodermaptera.

Investigating the effect of host plant identity on instar number in fall webworm, a common generalist herbivore.

For herbivorous insects with a broad diet breadth, host plant identity can influence larval development by either accelerating or delaying growth. For some species of Lepidoptera, the number of larval instars varies depending on the host plant's identity. Fall webworm (Hyphantria cunea, Drury) is a polyphagous herbivore that feeds on over 450 host plants worldwide. Of the 2 morphotypes (red- and black-head) of fall webworm, the number of instars for the red-head fall webworms has not been characterized. Given its broad diet breadth, fall webworm developmental stages may vary with plant identity. We investigated whether host plant identity affected the number of instars observed during red-head fall webworm development. We measured the head capsules of over 6,000 fall webworm larvae reared on 6 different plants commonly eaten by fall webworms in Colorado. We modeled head capsule widths as Gaussian mixture models, with a Gaussian distribution that corresponded to each instar. We show that our red-head fall webworms varied in number of instars depending on the identity of their host plant upon which they fed. We found that red-head fall webworm exhibited 7 instars on 5 of the host plants and 8 instars on 1 host plant that we studied. Our results for the number of instars for red-head fall webworm are consistent with reports of the number of instars for black-head fall webworm. Our research provides insight into the influence of host plant identity on fall webworm development, which can be used to advance lab and field research of this species.

Larval instars determination for the twig borer weevil (Coleoptera: Curculionidae) of Falcataria moluccana (Miq.) Barneby & Grimes in Moluccas, Indonesia

In establishing an integrated pest control strategy, it is important first to discover the life history of a potential agent, including the number of larval instars. The snout-weevil of the tribe Ithyporini Genus species (Coleoptera: Curculionidae) is a holometabolous insect that attacks Falcataria moluccana, a native tree of the Moluccas (Maluku), Indonesia. Preliminary observations show that their larvae feed and develop as a twig borer, making direct observation of their development complicated. This study aimed to determine the number of larval instars by measuring the head capsule width (HCW) and the growth pattern of larvae. As many as 940 larvae of all sizes were collected from three islands in Maluku Province: Ambon, Seram, and Haruku. Kernel density estimation (KDE) and Gaussian mixture model (GMM) were used for data analysis. The growth instars were verified using Brooks-Dyar’s rule. The results indicated four peaks in the frequency distribution from KDE, and cluster four showed the best-fit model from GMM. The growth ratio of HCW was 1.47, which also agrees with Brooks-Dyar’s rule that the growth ratio was consistent and followed a constant geometric. Thus, this research concluded that there were four instars for Ithyporini Gen. sp. larvae.

Immature stages of Phloeosinus tacubayae (Curculionidae: Scolytinae): morphology and chaetotaxy of larva and pupa, sexual dimorphism of adults, and developmental time.

The current knowledge of morphology and chaetotaxy of the different developmental stages within the subfamily Scolytinae presents an information deficit that needs to be addressed. Thus, the objective of the present study was to describe, the chaetotaxy and morphology of larvae and pupae, and determine the number of larval instars, the sexual dimorphism in adults, and the development time in Phloeosinus tacubayae. The number of larval instars was determined using traditional morphometry of cephalic capsule and multivariate analysis; description of morphology and chaetotaxy of larvae and pupae, and sexual dimorphism in adults was based on light microscopy and scanning electron microscopy photographs; finally, we quantified development time by mean reviews of 10 gallery systems selected randomly in infested logs, in the laboratory. Morphometric analysis of the cephalic capsule allowed the recognition of 3 different instars. Our results showed that the larvae of P. tacubayae have unique attributes in the body that differentiate them from other genera of the subfamily for example the epicranial suture is not marked, and differentiated from Phloeosinus canadensis, such as a smaller number of setae in the maxillae and without a tergal plate. The pupa had a smaller number of setae on the whole body. The most useful morphological characters to identify a sexual dimorphism in adults were found in the shape and relative position of the seventh and eighth tergites; development time lasted 40 days in total, being the pupal stage the one that took the longest to complete.

Unraveling the effect of temperature and humidity on the life cycle of Diatraea saccharalis (Lepidoptera: Crambidae) and the impact on pest outbreaks.

Temperature and humidity are considered the main abiotic factors that affect both the development and survival of ectothermic organisms. In this study, we estimated the development time as well as the thermal requirements of the sugarcane borer, Diatraea saccharalis (Fabricius, 1794; Lepidoptera: Crambidae), a key insect pest of sugarcane and discussed the influence of temperature and relative humidity and its infestation intensity in a scenario of climate change. The models Brière-1 and Ikemoto-Takai provided the best fit to the data of development rate versus temperature. The average life cycle (from egg to adult) ranged from 39.21 ± 4.84 at 32 °C to 137.10 ± 7.47 at 18 °C days. The thermal constant and average base temperature were 547.69 degree-days and 13.64 °C, respectively. The number of larval instars varied from 4 to 7 depending on the temperature, being higher at lower temperatures. The thermal range comprised the interval from 16.7 °C to 33.9 °C and the optimum temperature was estimated as 27.4 °C. Locations with elevated temperature (≥25 °C) and high relative humidity (≥70%) presented larger populations of D. saccharalis. Our findings show that the infestation pressure of this species is highly influenced by both temperature and humidity, and the studied models allow to forecast pest outbreaks. In the context of climate change, information about the thermal range and the optimum temperature contributes to predicting the spatial-temporal distribution of D. saccharalis and, consequently, aids decision making in pest management.

Sub-optimal host plants have developmental and thermal fitness costs to the invasive fall armyworm.

The fall armyworm (FAW) Spodoptera frugiperda (J.E. Smith) is a global invasive pest of cereals. Although this pest uses maize and sorghum as its main hosts, it is associated with a wide range of host plants due to its polyphagous nature. Despite the FAW's polyphagy being widely reported in literature, few studies have investigated the effects of the non-preferred conditions or forms (e.g., drought-stressed forms) of this pest's hosts on its physiological and ecological fitness. Thus, the interactive effects of biotic and abiotic stresses on FAW fitness costs or benefits have not been specifically investigated. We therefore assessed the effects of host plant quality on the developmental rates and thermal tolerance of the FAW. Specifically, we reared FAW neonates on three hosts (maize, cowpeas, and pearl millet) under two treatments per host plant [unstressed (well watered) and stressed (water deprived)] until the adult stage. Larval growth rates and pupal weights were determined. Thermal tolerance traits viz critical thermal maxima (CTmax), critical thermal minima (CTmin), heat knockdown time (HKDT), chill-coma recovery time (CCRT), and supercooling points (SCPs) were measured for the emerging adults from each treatment. The results showed that suboptimal diets significantly prolonged the developmental time of FAW larvae and reduced their growth rates and ultimate body weights, but did not impair their full development. Suboptimal diets (comprising non-cereal plants and drought-stressed cereal plants) increased the number of larval instars to eight compared to six for optimal natural diets (unstressed maize and pearl millet). Apart from direct effects, in all cases, suboptimal diets significantly reduced the heat tolerance of FAWs, but their effect on cold tolerance was recorded only in select cases (e.g., SCP). These results suggest host plant effects on the physical and thermal fitness of FAW, indicating a considerable degree of resilience against multiple stressors. This pest's resilience can present major drawbacks to its cultural management using suboptimal hosts (in crop rotations or intercrops) through its ability to survive on most host plants despite their water stress condition and gains in thermal fitness. The fate of FAW population persistence under multivariate environmental stresses is therefore not entirely subject to prior environmental host plant history or quality.

The number of larval instars in the flax weevil (Anagotus fairburni) (Coleoptera: Curculionidae)

ABSTRACT The flax weevil Anagotus fairburni is a large flightless beetle, that is one of the members of the endemic insect ‘megafauna’ of New Zealand. It is a protected species that currently persists only on predator-free islands or in remote and difficult to access alpine areas. Little is documented about the ecology of the flax weevil. In this study we estimated the number of instars in the A. fairburni life cycle by measuring the head capsule widths of larvae collected in the field on Mana Island Scientific Reserve. We used kernel density function estimates to predict average head-capsule widths and the number of larval instars. We then used Brooks-Dyar’s law on the head capsule width data and analysed Brooks and Crosby indexes to refine the estimated number of instars based on imperfect data. Results from sampling of 86 larvae suggested four instar groupings, but further analysis based on Brooks-Dyar’s law found that A. fairburni likely passes through 6 or 7 larval stages prior to pupation, with some uncertainty for smaller instars. Our method provides new data on ecology of an endemic species and provides a framework for further work on similar endangered species where data is imperfect or difficult to gather.

Developmental models and morphological characteristics of the hide beetle, Dermestes frischii, under different constant temperatures

Many species of hide, larder, and carpet beetles (Coleoptera, Dermestidae) are economically important pests of stored products of animal and plant origin, and also have high forensic application value. This study investigated the developmental duration of the immature stage of Dermestes frischii (Kugelann, 1792) under six constant temperatures (19, 22, 25, 28, 31, and 34 °C) and found that development was longest at 19 °C, taking 97.4 ± 7.9 days, and was shortest at 31 °C, taking 31.3 ± 7.2 days. The isomorphen diagram was established based on the developmental events under the different constant temperatures, and the thermobiological parameters of D. frischii were evaluated using linear thermal summation and curvilinear Optim SSI models. The thermal summation constant was 559.89, while the intrinsic optimum temperature and lower and upper lethal developmental thresholds were 24.65, 13.37, and 34.98 °C, respectively. The mortality rate and the mean number of larval instars increased under higher or lower temperatures. The mean instar duration of the first to the fifth instar was generally similar, while the instar duration was the shortest under high temperatures with the fastest developmental rate. We conclude that temperature has a separate effect on the number and duration of the larval instar of D. frischii. In addition, the larval morphological parameters were measured, and the ultrastructures of the antennae, mouthparts, and urogomphi were characterized. This work provides important basic data for storage pest control and minimum postmortem interval estimation of D. frischii in forensic entomology research and application.

The Life History and Ecology of the Lesser Wasp Moth, Pseudocharis minima, (Lepidoptera, Erebidae, Euchromiina) in the Pine Rocklands of South Florida

The Arctiinae species Pseudocharis minima (Lesser Wasp Moth) is considered imperiled according to Florida Natural Areas Inventory but little had been published on its life history. We describe the life history of the Lesser Wasp Moth descriptively and quantitatively while providing images of eggs, larval instars, pupae, and adults. We describe a variance in the number of larval instars from 6 to 8. We also report the first field observations of Lesser Wasp Moths utilizing Crossopetalum rhcoma (Maidenberry) for egg laying and larval consumption. The mean life-cycle duration is ∼61 days and can provide about 6 generations in a single year. We anticipate that our research will aid in the management of native pine rockland habitats for the Lesser Wasp Moth as well as laying the groundwork for conservation efforts in the event of possible further population declines.

Temperature-mediated developmental plasticity in winter and summer larvae of Palaemon serratus

In a seasonal environment, variation in larval phenotype and developmental plasticity allow crustacean larvae to maximise survival by lengthening or shortening their development. The aim of this study is to investigate the effects of temperature, laying season and their interaction on larval developmental pathways (larval instars and larval stages). We monitored the different larval stages and calculated the number of larval instars reached during the development of winter and summer larvae of Palaemon serratus incubated at 12, 16 or 20 °C. We observed a great variability in the larval development (6–13 larval instars and 6 to 11 larval stages). A higher temperature decreases the development time and the number of larval instars. At a given temperature, the development time of winter and summer larvae was not different. Two larval stages were considered supernumerary (zoea 4 and 6), as they were more frequent at low temperatures. At higher temperatures, some larvae started to develop pleopods as early as the third instar, larval stage which had never been described (named here zoea 3′). This phenomenon was more common in winter larvae than in summer larvae. These results provide new insights into the expression of developmental plasticity in decapod larvae.

Instar Determination for the Tomato Leafminer Tuta absoluta (Lepidoptera: Gelechiidae) Using the Density-Based OPTICS Clustering Algorithm.

The tomato leafminer Tuta absoluta (Meyrick) is one of the most harmful pests of solanaceous crops. Its larval morphological characteristics are similar, making the distinguishing between different larval instars difficult. Accurate identification of T. absoluta instars is necessary either for population outbreak forecasting, or developing successful control programs. Although a clustering algorithm can be used to determine the number of larval instars, little is known regarding the use of density-based ordering points to identify the clustering structure (OPTICS) and determine the number of larvae. In this study, larval instars of 240 T. absoluta individuals were determined by the density-based OPTICS clustering method, based on mandible width, and head capsule width and length. To verify the feasibility of the OPTICS clustering method, we compared it with the density-based spatial clustering of applications with noise (DBSCAN) clustering algorithm, Gaussian mixture models, and k-means. Additionally, the instars determined by the clustering methods were verified using the Brooks–Dyar rule, Crosby rule, and linear regression model. The instars determined by the OPTICS clustering method were equal to those determined by the other types of clustering algorithms, and the instar results were consistent with the Brooks–Dyar rule, Crosby rule, frequency analysis, and logarithmic regression model. These results indicated that the OPTICS clustering method is robust for determining insect larva instar phase. Moreover, it was found that three morphological indices of T. absoluta can be used for determining instars of this pest in the field, which may provide important information for the management of T. absoluta populations.

Larval Instars and Adult Flight Period of Monochamus saltuarius (Coleoptera: Cerambycidae)

Monochamus saltuarius is a vector of Bursaphelenchus xylophilus in Japan, South Korea, and the middle temperate zone of China. However, there are only a few reports on this species in China, and its biological characteristics are still unclear. In this study, we aimed to elucidate the larval development and adult flight period of M. saltuarius to provide a theoretical basis for the effective control of pine wilt disease in the middle temperate zone of China. Seven morphological variables of larvae were measured to determine the number of larval instars, and the adult specimens of M. saltuarius were collected from traps in forests to study the flight period of adults in Fushun, Liaoning, the epidemic center of pine wilt disease in the middle temperate zone of China. The results revealed that the full larval period of M. saltuarius was 279.6 d, and the larvae had five instar stages, with an average duration of 7.4, 14.3, 49.8, 83.6, and 124.5 d, respectively. Additionally, 78.4% of the overwintering larvae were fourth instar, and 21.6% were fifth instar larvae. We also found that the adults began to emerge from early May to late June, and the period was from early May to mid-August in the forest. During the investigations period from 2018 to 2020, the total number of adults captured was minimal at 744, and precipitation was highest at 291.54 mm in 2019. We characterized the larval instars and adult flight period of M. saltuarius, which is a prerequisite for developing appropriate management strategies. The results of this study will provide an important reference for the formulation of strategies to control M. saltuarius and pine wilt disease.

EFFECTS OF ARTIFICIAL DIETS ON THE BIOLOGICAL CYCLE OF Condylorrhiza vestigialis

The objective of this work was to determine the influence of different artificial diets on biological parameters related to the life cycle of C Condylorrhiza vestigialis aiming to determine the most suitable diet for the rearing of a population of this insect. Four diet formulations were tested. Ten repetitions were used, with 30 caterpillars per repetition. All stages of C. vestigialis life cycle were followed to evaluate biological parameters: viability of larvae, pre pupa, pupa and adults, as well as the sex ratio. The number of larval instars, the pupal mass and the total number of eggs per day and per female day were also calculated. The four diets tested allowed the development of C. vestigialis caterpillars. All diets were considered adequate for the purpose of the work, which is the production of baculovirus used in the control program of this pest. It was the diet 2 that provided the best results, the largest pupal mass, and the quantity and viability of the eggs produced by C. vestigialis females fed in this larval phase.

Host Plant and Thermal Stress Induce Supernumerary Instars in Caterpillars.

Environmental stressors may induce variation in the number of larval instars of holometabolous insects. Host plant quality and ambient temperature can both induce this life history shift in the silver-spotted skipper, Epargyreus clarus (Cramer 1775) (Lepidoptera: Hesperiidae). To better understand this phenomenon, we raised larvae on high-quality (kudzu) or low-quality (wisteria) host plants in growth chambers under three temperature regimes (20, 26, and 32°C) that were either constant or diurnally fluctuating (T ± 5°C), and recorded survival and incidence of supernumerary instars. Larvae feeding on the low-quality host and/or experiencing thermal stress were more likely to show supernumerary development (SD). A subset of treatments yielded a mix of SD and TD (typical development) individuals, allowing for comparisons between phenotypes. Under the most stressful treatment (20 ± 5°C, wisteria), development time was 9 days longer in SD than in TD individuals; by contrast, at typical summer temperatures (26 ± 5°C), also on wisteria, total development time did not differ between these two phenotypes. Head capsules of both second and third instars were smaller in SD individuals. A retrospective logistic regression analysis indicated that third-instar head capsule size could be used to predict expression of the SD phenotype. By the ultimate instar, however, there were no detectable differences in head capsule size, and SD and TD individuals did not differ in pupal mass, strongly suggesting that the SD phenotype functions as a compensatory mechanism allowing E. clarus larvae to achieve the same size at metamorphosis (a strong fitness correlate) as TD larvae.

A Comparison of Three Approaches for Larval Instar Separation in Insects-A Case Study of Dendrolimus pini.

The number of larval instars is important from both theoretical and practical perspectives. Three previous studies based on head capsule widths (HCWs) have suggested that Dendrolimus pini larvae pass through seven instars, but the estimated HCW means differed greatly. Various methods are available for determining the number of instars; however, these methods have not been compared on the same dataset. Therefore, the main goal of this study was to compare three approaches for instar separation in D. pini larvae: visual approach followed by non-linear least squares (NLLS) estimation, kernel density estimation (KDE) followed by NLLS, and model-based clustering. Two criteria were used to assess whether the resulting instar separations adhered to Brooks-Dyar’s rule: Crosby’s growth rule and a coefficient of determination indicating the goodness of fit of a straight line to the ln-transformed mean HCW of the respective instars. Our results showing that D. pini larvae pass through eight instars differed greatly from reports in the literature. The best results were obtained by KDE followed by NLLS. For proper instar separation, both criteria of Brooks-Dyar’s rule must be met.

Diapause and biological cycle of Cydalima perspectalis (Walker) in the eastern Pyrenees

AbstractBoxwood is a very important component of the natural forests of the eastern Pyrenees. In the low altitudes of these forests, the invasive species Cydalima perspectalis (Walker) causes considerable damage, and there is concern that it will migrate towards the natural forests at higher altitudes. To determine the biological parameters of the local pest population, a semiartificial diet with lyophilized powdered Buxus sempervirens L. leaves was developed. The results obtained indicate that the studied population of C. perspectalis is very similar to the native Japanese population in terms of the number of larval instars to complete development, the development rate and the critical photoperiod for the induction of diapause. It has also been demonstrated that long photoperiods can shorten the duration of larval development. The diapause induction response was classified as type I, and diapause termination was classified as type III. At the two studied temperatures, 25º and 15ºC, the larvae seemed to require a similar number of days in diapause, approximately 3 months, to spontaneously resume development; temperatures can also prompt larvae to resume development. The critical photoperiod in the study area occurs during the second half of August, varying somewhat according to temperature. The greatest defoliation is caused by the offspring of the first generation, while the majority of the larval offspring of the second generation will enter diapause. The survival of natural boxwood in this area will depend on its ability to regrow one or two years after extensive defoliation and on the adaptation of several indigenous natural enemies in the region to feed on C. perspectalis.

Cleonis pigra (Scopoli, 1763) (Coleoptera: Curculionidae: Lixinae): Morphological Re-Description of the Immature Stages, Keys, Tribal Comparisons and Biology.

Mature larvae and pupae of Cleonis pigra (Scopoli, 1763) (Curculionidae: Lixinae: Cleonini) are morphologically described in detail for the first time and compared with known larvae and pupae of other Cleonini species. The results of measurements and characteristics most typical for larvae and pupae of Cleonini are newly extracted and critically discussed, along with some records given previously. Keys for the determination of selected Cleonini species based on their larval and pupal characteristics are attached. Dyar’s law was used for the estimation of a number of larval instars of C. pigra. Descriptions of habitats, adult behavior, host plants, life cycle, and biotic interactions are reported here. Adults and larvae feed on plants from the Asteraceae family only (genera Carduus, Cirsium, Centaurea, and Onopordum). Oviposition occurs on the base of the plant stem or the root neck. In the process of larval development, a fusiform gall forms. C. pigra and Cyphocleonus achates can coexist in the same locality. In open habitats, the weevils become the prey of carnivorous animals.

Biology and host selection stage of Symmetrischema dulce Povolny (Lepidoptera: Gelechiidae) in chili pepper.

The pepper-fruit-borer Symmetrischema dulce Povolny (Lepidoptera: Gelechiidae) is an important chili pepper pest causing significant yield losses. However, chili pepper has insufficient crop protection support and primary information about S. dulce is scarce. In the present study, we aimed to study the biology and ecology of S. dulce in pepper plants (Capsicum frutescens L.) focusing to support integrated pest management programs. In the field, we sampled ripe and unripe chili pepper fruits in three different plant strata. In the laboratory, we established colonies of the S. dulce and we recorded the duration, viability, morphology of each life stage, and number of larval instars. We conducted experiments to evaluate insect reproduction, whereby we registered the pre-oviposition and oviposition period, daily oviposition rate, and sex ratio. From these results, we estimated the reproductive success of S. dulce through the intrinsic population growth rate. The higher occurrence of S. dulce was in unripe fruits with no difference between plant strata. Egg stage lasted 4days with 94% viability, and larval phase lasted on average 10.72days and presented four instars with viability of 66.6%. Pupal stage lasted 9.61days with viability of 94.73%. The adult stage lasted 24.14days with a pre-oviposition period of 3days and oviposition period of 13.85days. The intrinsic growth rate (rm) recorded was 0.0035. Our results suggest that the biology of S. dulce has similarities with other Lepidoptera, but its peculiarities in reproductive parameters are essential for future programs of pest management.

Descriptions of immature stages of four species of the genera Graptus, Peritelus, Philopedon, and Tanymecus and larval instar determination in Tanymecus (Coleoptera, Curculionidae, Entiminae).

The mature larva and pupa of Graptustriguttatustriguttatus and the mature larva of Peritelussphaeroides are described for the first time. The larvae of Philopedonplagiatum and Tanymecuspalliatus are re-described. Five larval instars were determined in Tanymecus, thereby correcting doubtful data in the literature. The relationship between larval growth, number of larval instars, head width of the mature larva, and the adult weevil is explained using the example of Tanymecus. The nearly constant ratio of subsequent larval instars in head width ratio, termed “growth factor” and derived from Dyar’s ratio, is used for the determination of larval instars. Larval collecting and breeding data are discussed in relation to their significance for the clarification of life-cycles.

Unusual cases of product contamination by 'wandering' larvae of the Indian meal moth, Plodia interpunctella (Lepidoptera: Pyralidae):

Upon hatching, the larvae of the Indian meal moth (IMM), Plodia interpunctella, disperse vigorously. Within a few hours, they establish themselves on the crevices of food or enter packaged product through small openings and cracks. When on food the larvae intensively feed in or near a tunnel-like case made of frass and silk they web together. The number of larval instars varies from five to seven, depending on temperature, humidity and available food quality. Most mature larvae leave the food medium and search for a suitable place to spin a cocoon in which they pupate or hibernating (diapause). At the end of larval development, the larvae usually chews a hole in a packaging foil, and leave the medium to pupate outside in corners and cracks and also behind items on walls. Fully grown larvae of the IMM may travel a considerable distance before pupating in a location that is frequently away from the larval food source. It will be proven and illustrated that during this time larvae the IMM may penetrate the packaging material of some household items that were not their food source. Unusual cases of product contamination by 'wandering' larvae will be described. Client claims are thus frequent as only a few larvae in a package with their webbing and frass are very repulsive to homeowners. Impact of product contamination by 'wandering' larvae of the IMM to the firm marketing the products will be discussed.