Pyralidae

Moths in this large family are small and have a wing span of about 27 mm. Front wings are elongate or triangular, and the hind wings are usually broad. The proboscis has scales and the labial palps often project forward, giving this group the name snoutmoths. All species have abdominal tympanal organs, and many are active at night. This family includes species that are aquatic and have caterpillars that breathe by means of gills, species that are pests of ornamental and agricultural grains, and in foods in storage.

The origin ofpyralid pests ofstored foods is linked to their natural habitats and their ability to adapt to the indoor environment. Some species were originally associated with the habitats of other animals, such as the nests of bees, birds, and small rodents. Several species naturally infest ripe grains in the field, but readily adapted to indoor conditions to become pests of the harvested and stored grain. Many of the pests of dry nuts and fruits were associated with the natural products either on the tree or ripened and on the ground. The moths associated with stored grain are general scavengers on a variety ofplant materials. Many of the species that occur indoors are also represented by populations in natural or undisturbed areas.

Caterpillars of some pyralid species secrete kairomones from their mandibular glands, and the quantity of these chemicals increases as caterpillar density increases. The concentration of these chemicals causes increased wandering by the late-stage caterpillar, and affects adultoviposition. Caterpillars

How Draw Shadow Object
Figure 11.4 Lepidoptera: Pyralidae. (a) Pyralis farinalis adult; (b) P. farinalis front and hind wings; (c) Corcyra cephalonica; (d) Paralipsa gularis; (e) Galleria mellonella; (f) Ephestia elutella; (g) Aglossa caprealis; (h) Vitula edmandsii serratilinella.

of most pyralids are negatively phototactic until they are about to pupate. They are also sensitive to crowding and this condition can delay development and result in small caterpillars and adults. Most of the stored-food pyralids produce sex pheromones. The chief component of the female pheromone of several species is cis-9, trans-12-tetradecadien-i-yl acetate. Within 24 h of emergence females assume the calling posture, in which the abdomen is lifted between the wings and the scent glands are extruded. Males locate females by flying against air currents and orient using the concentration of the pheromone in the air stream. Sex pheromones have been extracted from the wing glands of male Ephestia elutella and Plodia interpunctella. The rapid wing beating of males prior to mating may disperse these chemicals, which appear to be important in the final stage ofcourtship. The pheromones released from male P. interpunctella produce a turning response in receptive females.

Lesser wax moth, Achroia grisella (Fig. 11.1c) Adult wing span is 17-21 mm, the body is brown, and the head is yellowish brown. Front wings are mottled. The full-grown caterpillar is 15-18 mm long, slender, and yellowish white to gray. The head is brown, and the ocelli are absent. Thoracic segment i has a dark brown dorsal plate. Caterpillars feed on stored foods and dried fruits, and are also found in wild and commercial honey bee hives, especially in the debris at the bottom and, less often, in the combs. This species is cosmopolitan.

Murky meal moth, fungus moth, Aglossa caprealis (Fig. 11.4g; 11.5a) Adult female wing span is 9-10 mm; the male moth body is 13 mm long, and the female 16 mm long. The body is dark brown and the wings have light brown markings. Full-grown caterpillars are about 20 mm long, shiny dark brown to brownish black. The caterpillars are usually active in dark and damp locations where wood-decay fungi, such as Poria incrassata, develop. The surface of decay fungi is often covered with webbing produced by the caterpillar. When full-grown, caterpillars migrate before pupation, and are usually found away from their feeding site.

Mediterranean flour moth, Anagasta kuehniella (= Ephestia) (Fig. 11.2e; 11.5b) Adults are 7-12 mm long and have a wing span of about 22 mm; the frontwings are pale gray with transverse, irregular bands; hind wings are grayish white. When at rest, the adult raises its front wings and elevates the anterior of the body. Full-grown caterpillars are about i5 mm long, yellowish white to pinkish white, and have a brown head. Eggs are laid singly; fecundity is 100-600 eggs. Oviposition can occur at 7.5 °C, but not at 5 °C. Hatching is between 10 and 31 °C, and is in 5 days when eggs are deposited at 25 °C, and 4 days when deposited at 30 °C. Eggs survive exposure to —10 °C for 5 days. Development is completed in 10 weeks at 25 °C and

Figure 11.5 Lepidoptera: Pyralidae larvae. (a) Aglossa caprealis, head and thorax 1, 2, and abdomen segment 4; (b) Anagasta kuhniella, head and prothorax; (c) Pyralis farinalis, head, thorax segments 1, 2, and abdomen segment 4; (d) Ephestia elutella, head, thorax segments 1, 2, and abdomen segment 4; (e) Plodia interpunctella, head and thorax segments 1, 2, and abdomen segment 4; (f) Tinea pellionella, dorsal view of head and prothorax; (g) Tineola bisselliella, dorsal view of head and prothorax.

nests of bumble bees, but they migrate before pupation and invade houses before they spin a cocoon.

Almond moth, tropical warehouse moth, Cadra cautella (= Ephestia) Adults are about 12 mm long, and have a wing span of about 14-22 mm. Front wings are reddish brown with indistinct white cross lines, while hind wings are uniformly pale gray with short fringe hair. The proboscis is rudimentary. Adults fly with rapid wing movements, and move quickly. Full-grown caterpillars are about 12 mm long, yellowish white, and with a uniformly brown head. Body segments have small, pigmented spots. Eggs are laid singly or in small batches; hatching occurs between 15 and 37.5 °C. Eggs hatch in about 17 days at 25 °C and 70% RH, 7-8 days at 15 °C, 4-5 days at 25 °C, and 3 days at 30 °C. Exposure to —10 °C for 9 h kills 95% of eggs. Development is longer at low RH; caterpillars survive above 0 °C. At 70% RH, the range of temperature for development is 15-36 °C; developmentis 30 days at30-32 °C and 70-80% RH when immatures are reared on a mix ofwheatfeed, wheat germ, and yeast. Diapause is influenced primarily by temperature and photoperiod. Caterpillars are more responsive to continuous darkness than to short photoperiods or continuous light.

Figure 11.5 Lepidoptera: Pyralidae larvae. (a) Aglossa caprealis, head and thorax 1, 2, and abdomen segment 4; (b) Anagasta kuhniella, head and prothorax; (c) Pyralis farinalis, head, thorax segments 1, 2, and abdomen segment 4; (d) Ephestia elutella, head, thorax segments 1, 2, and abdomen segment 4; (e) Plodia interpunctella, head and thorax segments 1, 2, and abdomen segment 4; (f) Tinea pellionella, dorsal view of head and prothorax; (g) Tineola bisselliella, dorsal view of head and prothorax.

75% RH on white flour. The lower limit for development is abouti2 °C; itcan be completed at28 °Cbutnotat3i °C. Males become sterile when reared at30 °C, and rearing in continuous light also induces male sterility. Pupae are in cocoons, or not when they are in cracks or crevices; the pupal period lasts 8-12 days. There are four or five generations per year. Food infested includes flour, nuts, seeds, beans, dried fruits, and chocolate. The silk produced by the caterpillars may be thick in infested areas; developing caterpillars usually remain in their silk feeding tubes. Full-grown caterpillars may be found far from the infested site.

Wax moth, Aphomia sociella This moth is a pest indoors in northern Europe (Denmark). The caterpillars develop in the

Feeding at 25 °C rather than 20 °C limits diapause in most strains. Diapause in this species lasts about 4 months, even under constant conditions, and exposure to temperatures slightly below development threshold terminates diapause in about 30 days. The pupal stage lasts about 18 days at 20 °C, gdays at25 °C, and/daysat30 °C. Caterpillars feed on cereals, cocoa beans, dried fruits, flour, grain, peanuts, various seeds, and shelled nuts. This species has a worldwide distribution, especially in warm parts of the world.

Adults are mainly nocturnal, and become active in late afternoon and evening in response to changes in light intensity and temperature; they mate and lay eggs after dusk. They have a peak of activity in late evening and a second but smaller peak just before dawn. The visual system of C. cautella responds most strongly in the yellow-green and ultravioletregions of the spectrum. The peak of spectral efficiency in the green region may be employed during motion detection or during the orientation towards yellow-green pigmented plants containing nectar.

Raisin moth, Cadra figulilella (= Ephestia) Adults are about 10 mm long and the wing span is 15-20 mm. The front wing is gray and the hind wing is shiny white; both wings have a long fringe ofhairs at the margins. Full-grown caterpillars are about 13 mm long, yellowish white, and have four rows of purple spots along the back. Eggs are scattered over the surface of the host fruit; fecundity is about 350 eggs. Hatching is in about 4 days, but only 10% hatch at 15 °C, and none below. Developmentrequires about30 days; limits for complete development at 75% RH are at 15 °C and 36 °C. The low RH limit is 30-50% RH. Optimum conditions for survival and development are about 30° C and 70% RH. On wheatfeed, yeast, and glucose, development from egg to adult is about 36 days, and increases to 122 days at 17.5 °C. Development is about 34 days on ground carobs and 56 days on almonds at 30 °C and 70% RH. Diapause is in response to photoperiods of 13 h or less; at constanttemperatures some caterpillars remain in diapause for about 1 year; in field populations mostpupate after 3-5 months in diapause. This is a pest of ripening fruit in the orchard or partially dried fruitin storage; itis also known to feed on cereals and nuts. Damage to dried fruit, such as raisins, includes the caterpillars feeding on the surface of the fruit and the resulting fecal pellets and webbing. It has worldwide distribution, and is one of the most common pests of dried fruits.

Rice moth, Corcyra cephalonica (Fig. 11.4c) Adult wing span is 14-24 mm, and the body and wings are grayish brown; the wings are withoutdistinct bands. The male has shortand blunt labial palps, while the female has long and pointed palps. Adults fly at night. Full-grown caterpillars are 12-14 mm long, and yellowish white to bluish gray, and sometimes have a green tint. Caterpillars have long fine hairs on the body and a dark brown head and brown prothoracic shield. There is a seta above each spiracle, starting with abdominal segment 1; the posterior rim of the spiracles is thickened. Eggs are somewhat sticky and they are deposited directly on flour or other host food; fecundity is 100-300 eggs. Hatching is in 10 days at 20 °C and 4 days at 30 °C. Development from egg to adult is 26 days at 30-32.5 °C and 70% RH. Development on sorghum is 46-55 days at 28 °C and 70% RH, and on millet it is 31-41 days. Limits for development are 17 °C and 35 °C at 70% RH. The last stage spins a tough, double-layer cocoon covered by food particles and debris. This species feeds on stored rice, cocoa, nuts, and flour. Damage is done by directfeeding ofthe caterpillars, and by the tough silk webbing on the infested material. In hot and humid climates, itis a major pest in flourmills. Caterpillars produce dense webbing, and when feeding on grains they spin dense silken tubes and web the grain kernels into the walls of the tube. As its scientific name implies, this species was described from the Grecian archipelago, but it has spread from there. It is nearly cosmopolitan throughout the tropics, and it is abundant in Southeast Asia, and common in Africa.

Grass moth, Crambus flexuosellus Adults are about 12 mm long. The wings are paleyellowand usually wrapped around the body. Frontwings have scattered brown markings and the front margin is bordered with a brown stripe and a broad white stripe. Full-grown caterpillars are about 12 mm long and brownish red. Caterpillars feed at night, and chew long narrow holes in the blades of grass; they sometimes burrow into the stem. Caterpillars also attack the roots of small plants. They remain in silken retreat in the soil during the day. Adults often fly to lights at night. This species occurs in New Zealand.

Sod webworms, lawn moths, Crambus spp. and Pediasia spp.

Adults are 12-20 mm long and the body is gray to grayish white. The maxillary palps are long and give the head a distinct snout appearance. Full-grown caterpillars are 16-20 mm long and the body is brownish white. The head is dark brown and segments have dark brown sclerites. They remain in silk retreats at the soil or thatch layer of turfgrass, and other ground-cover vegetation. Adults remain inactive on low vegetation during the day, and become active at dusk and for 2-3 h after. They have an erratic flight pattern, stopping atnumerous sites to rest and oviposit. Eggs are laid singly or in small batches while the female rests on blades of grass or plant stems. Eggs are small, somewhat barrel-shaped, and drop into the organic layer or soil. Fecundity is about 250 eggs. Hatching occurs in about 7 days, and eggs turn from white to reddish orange before the first stage emerges. Development is completed in about 3 weeks, and full-grown caterpillars pupate in a cavity formed in the thatch or soil. The pupal period is about 10 days. There are 1-3 generations per year.

Carob moth, dried fruit moth, Ephestia calidella Adults are about 12 mm long, and the body is grayish brown. The wing span is 19-24 mm; the front wing is grayish brown or brown with two cross-lines, while the hind wing is pale gray. Full-grown caterpillars are about 14 mm long, yellowish white, and have a dark head. At 30 °C and 70% RH development is complete in 27 days on wheatfeed, 41 days on carobs, and 59 days on almonds. This species is nearly cosmopolitan. In the UK the feeding period is September to May, and the adults fly in August and September.

Tobacco moth, cocoa moth, warehouse moth, Ephestia elutella (Fig. 11.4f; 11.5d) Adult are 5-9 mm long and the wing span is 14-20 mm; the body is grayish brown. Front wings have two pale regions. Full-grown caterpillars are 10-18 mm long and yellowish white; sometimes they are slightly brown or pink, and have a brown head. Eggs are deposited singly at dusk or night during the first week after emergence; fecundity is 150-200 eggs, but327 and 500 eggs from one female have been reported. Eggs hatch in about 20 days at 15 °C, 10 days at 20 °C, 6-7 days at 25 °C, and 4-5 days at 30 °C. Fecundity and longevity are increased by about 30% when water is available. The temperature range for development is 10-30 °C.Developmentfromegg to adult in wheatlings, yeast, and glycerol takes 6-7 weeks at 25 °C and 70% RH, and 11-12 weeks at 20 °C. Caterpillar diapause usually lasts 6-8 months and is stimulated by exposure of the recently molted last stage to photoperiods of 14 h or less, or to temperatures of 20 °C or below. Termination of diapause occurs when there is an extended period oftemperatures from 5 to 10 °C, followed by a period when temperatures are above 20 °C. The pupal period is 6-7 weeks at 15 °C, 12-15 days at 25 °C, and 10-11 days at 30 °C. In warehouses, adults live up to 3 weeks. Caterpillars feed on a variety of dry fruits and vegetables, including tobacco, cereals, chocolate, cocoa beans, coffee, flour, nuts, seeds and spices. On most foods development is relatively slow. This species is nearly cosmopolitan, but is not common in the tropics. In the UK and Europe it survives outdoors and in unheated buildings.

Greater wax moth, Galleria mellonella (Fig. ii.id; ii.4e)

Adult wing span is 28-30 mm; the gray or pale brown body is marked with black tubercles on the fore wing, and the tips ofthe wings are gray. Males are smaller than females and lack maxillary palps. Full-grown caterpillars are 23-28 mm long, and the body color ranges from yellowish white to brown, with a dark brown to black prothoracic region and dorsum. The head is dark brown, with four pairs of ocelli. The thoracic spiracle has a yellow peritreme of uniform thickness. It infests abandoned or weakened bee nests, and can enter buildings from nests behind walls or in attics. It is an Old-World species, but is distributed in the USA and other regions where honey bees are kept. Eggs are laid atnighton or near the comb, and hatching is in 10-12 days. The caterpillar burrows through the hive comb and feeds on wax, excrement, and exuviae of the bees; the feeding tunnels are lined with silk. Pupation occurs in white, thick cocoons, which are spun during the nightalong the edge of the comb, and in cracks and crevices of the hive. Development varies from 45 days for the first generation to 35 days for the second and third-generation; some of the third-generation caterpillars overwinter. Adults are active at night, but remain motionless in the hives during the day.

Stored-nut moth, Paralipsa gularis (Fig. ii.4d) Adult wing span is about 21 mm, and the body and legs are yellowish brown; the fore wings are light brown and the hind wings yellowish brown. Full-grown caterpillars are about 18 mm long, yellowish white, and with a brown head. They feed on seeds, flour, nuts, and dried fruits, peanuts, soybeans, and some cereals. Eggs are laid singly or in small batches; fecundity is 150250 eggs; hatching occurs in 4-5 days at 30 °C. Development is completed in 12-15 weeks at 24 °C, and about 6 months at 18-20 °C. Full-grown caterpillars enter diapause in response to temperatures below 22 °C. Most diapausing caterpillars reared at 31 °C pupate after 3-4 months' exposure to 15-18 °C. It occurs principally in south Asia, including India, China, and Japan, but it has spread to other regions of the world.

Indian meal moth, Plodia interpunctella (Fig. ii.2d; ii.5e)

Adult wing span is 6-20 mm, the wings are pale gray, and the outer portion of the fore wing is reddish brown. The body is 6-8.5 mm long; the labial palps extend forward. Full-grown caterpillars are 10-13 mm long and yellowish white, but may be greenish or pinkish white; the head is dark brown. Caterpillars are distinguished from Ephestia by not having dark spots at the bases of the setae (one spot per seta), and the rim of the spiracles is weakly sclerotized. Eggs are deposited at night, in batches of 39-275, and usually 3 days after females emerge; fecundity is 150-400 eggs. Hatching is in 7-8 days at 20 °C, 4-5 days at 25 °C, and 3-4 days at 30 °C; no eggs hatch at 15 °C. Development is at temperatures between 18 and 35 °C, and is completed in about 60 days at 20 °C, 30 days at 25 °C, and 25 days at 30 °C. Young caterpillars survive temperatures down to 10 °C. The number of caterpillar stages varies from 5 to 7. Diapause extends development periods. It is generally linked to photoperiods ranging from 12.5 to 13.5 h, but the intensity varies with individual strains. In some, diapause may be induced at about 20 °C, and last no longer than 2-4 months, while in other strains diapause is induced by temperatures above 25 °C, and can last for up to 9 months. Full-grown caterpillars move away from the infested site to pupate; they wander for many hours before stopping to make a cocoon. Dia-pausing, full-grown caterpillars wander for 36-48 h at about 26 °C; nondiapausing caterpillars wander for 12-24 h at 27 °C. The pupal period is 15-20 days at 20 °C, 8-11 days at 25 °C, and 7-8 days at 30 °C. Under favorable conditions there may be 18 generations per year. Adults may not remain close to the infested material. They are weak flyers, usually in a zigzag pattern, and remain at rest for long periods on walls, usually facing upwards.

This species is a major pest of packaged food in transit and storage. Starved fourth- and fifth-stage caterpillars are capable of making entry holes in bags made of 0.03-mm-thick polyethylene containing suitable food. First-stage caterpillars invade food containers through holes of 0.27 mm diameter or greater, and they can travel 38 cm in search of entry holes. Adults can pass through holes 3 mm diameter or greater, but will oviposit on the surface of containers holding suitable food, and generally avoid laying eggs on empty containers. Caterpillars generally prefer coarse grades of flour, wholewheat or graham flour, maize, and cornmeal. In household and commercial sites this insect infests broken grain and grain products, such as flour and meal, dried fruits and nuts, seeds (especially birdseed), powdered milk, chocolate, and dry pet food. These and adjacent products may be covered by extensive webbing. P. interpunctella has been reported infesting the body cavity of domestic cats and an Indian ring-necked parakeet. A live P. interpunctella caterpillar was recovered from the brain cavity of a male parakeet, and live caterpillars were excised from subcutaneous tissue in two domestic cats. This species has a cosmopolitan distribution in commercial and residential environments.

Meal moth, Pyralis farnalis (Fig. 11.4a, b; 11.5c) Adult wing span is about 25 mm, and the front wings are light brown in the middle and dark brown at the base and the tip. The wings are held slightly spread when the moth is at rest. Full-grown caterpillars are 20-25 mm long and the body is slightly gray; the head is black and the posterior is pale orange. Infested food has extensive silk matting over the surface. It feeds on flour, meal, damaged grain, seeds, sesame cake, peanuts, and vegetable refuse. They are common in flour-processing and storage facilities, and prefer damp and spoiled grain and flour. It occurs in damp locations where there is mold growth. Eggs are scattered on the food surface; fecundity is 200-400 eggs. Caterpillars feed from tubes of silk, which contain particles of food. Development is completed in about 2 months, while overwintering is in diapause. It has a wide distribution in temperate regions of Europe and North America.

Other Pyralis Two other species that are pests of dried and stored grains and seeds include P. manihotalis and P. pictalis. Adults of P. manihotalis are uniformly pale brown, and the wing span is 24-37 mm. This species is endemic to South America, but now occurs in Africa, Asia, and Pacific Islands. It feeds on dried foods, tubers, dried meats, and hides. P. pictalis feeds on stored grains. The front wing is basally black and distally reddish brown, while the hind wing is dark basally and pale distally. This species is nearly cosmopolitan.

Dried fruit moth, Vitula edmandsii serratilinella (= V. edmand-sae) (Fig. 11.4h) Adult wing span is about 30 mm, and the body and wings are mottled gray. Full-grown caterpillars are about 18 mm long; the body is pale white or pinkish white and the head, thoracic shield, and anal plate are dark brown to black. This insect develops in dried fruits, especially those slightly fermented, and it has been recorded in rotting bee combs. It has been found in the cells of carpenter bees, Xylo-carpa tabaniformis orpifex, where caterpillars were feeding on stored pollen.

Other Pyralidae Caterpillars of Ectomyelois ceratoniae feed on stored almonds, and other nuts, and also dried fruit, stored carob pods, and seeds in Europe, Middle East, and Africa. Hypsopygia mauritialis adults have a wing span of about 15 mm; the front wings are dark with two pale spots. This species is recorded from Africa, India, China, Taiwan, Japan, Malaysia, Australia, and Hawaii. In Hawaii the caterpillars feed in old nests of vespid wasps. Corcyra cephalonica is a common pest of stored food products in Europe, and it has been introduced into the USA. In Australia, caterpillars of Sclerobia tritalis damage couch grass growing in lawns; this species occurs as far north as Maryborough in Queensland; Calamotropha cuneiferellus damages lawns in the east and north of Australia.

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