Life-cycle phases of the monarch or wanderer butterfly, Danaus plexippus. (After photographs by P.J. Gullan.)

Box 6.1

Figure 6.1 Schematic drawing of the life cycle of a non-biting midge (Diptera: Chironomidae, Chironomus) showing the various events and stages of insect development.

Figure 6.2 The life cycle of a hemimetabolous insect, the southern green stink bug or green vegetable bug, Nezara viridula (Hemiptera: Pentatomidae), showing the eggs, nymphs of the five instars, and the adult bug on a tomato plant. This cosmopolitan and polyphagous bug is an important world pest of food and fiber crops. (After Hely et al )

Figure 6.3 Life cycle of a holometabolous insect, a bark beetle, Ips grandicollis (Coleoptera: Scolytinae), showing the egg, the three larval instars, the pupa, and the adult beetle. (After Johnson & Lyon 1991.)

Figure 6.4 Stages in the development of the wings of the small white, small cabbage white, or cabbage white butterfly, Pieris rapae (Lepidoptera: Pieridae). A wing imaginal disc in a (a) first-instar larva, (b) second-instar larva, (c) third-instar larva, and (d) fourth-instar larva; (e) the wing bud as it appears if dissected out of the wing pocket or (f) cut in cross-section in a fifth-instar larva. ((a–e) After Mercer 1900.)

Figure 6.5 Embryonic development of the scorpionfly Panorpodes paradoxa (Mecoptera: Panorpodidae): (a–c) schematic drawings of egg halves from which yolk has been removed to show position of embryo; (d–j) gross morphology of developing embryos at various ages. Age from oviposition: (a) 32 hours; (b) 2 days; (c) 7 days; (d) 12 days; (e) 16 days; (f) 19 days; (g) 23 days; (h) 25 days; (i) 25–26 days; (j) full grown at 32 days. (After Suzuki 1985.)

Figure 6.6 Examples of larval types. Polypod larvae: (a) Lepidoptera: Sphingidae; (b) Lepidoptera: Geometridae; (c) Hymenoptera: Diprionidae. Oligopod larvae: (d) Neuroptera: Osmylidae; (e) Coleoptera: Carabidae; (f) Coleoptera: Scarabaeidae. Apod larvae: (g) Coleoptera: Scolytinae; (h) Diptera: Calliphoridae; (i) Hymenoptera: Vespidae. ((a,e–g) After Chu 1949; (b,c) after Borror et al. 1989; (h) after Ferrar 1987; (i) after CSIRO 1970.)

Figure 6.7 Examples of pupal types. Exarate decticous pupae: (a) Megaloptera: Sialidae; (b) Mecoptera: Bittacidae. Exarate adecticous pupae: (c) Coleoptera: Dermestidae; (d) Hymenoptera: Vespidae; (e,f ) Diptera: Calliphoridae, puparium and pupa within. Obtect adecticous pupae: (g) Lepidoptera: Cossidae; (h) Lepidoptera: Saturniidae; (i) Lepidoptera: Papilionidae, chrysalis; (j) Coleoptera: Coccinellidae. ((a) After Evans 1978; (b,c,e,g) after CSIRO 1970; (d) after Chu 1949; (h) after Common 1990; (i) after Common & Waterhouse 1972; (j) after Palmer 1914.)

Figure 6.8 The nymphal–imaginal molt of a male dragonfly of Aeshna cyanea (Odonata: Aeshnidae). The final-instar nymph climbs out of the water prior to the shedding of its cuticle. The old cuticle splits mid-dorsally, the teneral adult frees itself, swallows air, and must wait many hours for its wings to expand and dry. (After Blaney 1976.)

Figure 6.9 Schematic diagram of the classical view of endocrine control of the epidermal processes that occur in molting and metamorphosis in an endopterygote insect. This scheme simplifies the complexity of ecdysteroid and JH secretion and does not indicate the influence of neuropeptides such as eclosion hormone. JH, juvenile hormone; PTTH, prothoracicotropic hormone. (After Richards 1981.)

Figure 6.10 Diagrammatic view of the changing activities of the epidermis during the fourth and fifth larval instars and prepupal (= pharate pupal) development in the tobacco hornworm, Manduca sexta (Lepidoptera: Sphingidae), in relation to the hormonal environment. The dots in the epidermal cells represent granules of the blue pigment insecticyanin. ETH, ecdysis-triggering hormone; EH, eclosion hormone; JH, juvenile hormone; EPI, EXO, ENDO, deposition of pupal epicuticle, exocuticle, and endocuticle, respectively. The numbers on the x axis represent days. (After Riddiford 1991.)

Figure 6.11 A flow chart of the events prior to metamorphosis that determine body size in the tobacco hornworm, Manduca sexta (Lepidoptera: Sphingidae). During the last larval instar there are three physiological decision points. The final size of the insect is determined by the amount of growth that occurs in the intervals between these three conditional events. (After Nijhout et al )

Figure 6.12 Growth and development in a marine midge, Telmatogeton (Diptera: Chironomidae), showing increases in: (a) head capsule length; (b) mandible length; and (c) body length between the four larval instars (I–IV). The dots and horizontal lines above each histogram represent the means and standard deviations of measurements for each instar. Note that the lengths of the sclerotized head and mandible fall into discrete size classes representing each instar, whereas body length is an unreliable indicator of instar number, especially for separating the third- and fourth-instar larvae.

Figure 6.13 Age-specific oviposition rates of three predators of cotton pests, Chrysopa sp. (Neuroptera: Chrysopidae), Micromus tasmaniae (Neuroptera: Hemerobiidae), and Nabis kinbergii (Hemiptera: Nabidae), based on physiological time above respective development thresholds of 10.5, −2.9, and 11.3°C. (After Samson & Blood 1979.)

Box 6.2

Figure 6.14 Solitary and gregarious females of the migratory locust, Locusta migratoria (Orthoptera: Acrididae). The solitaria adults have a pronounced pronotal crest and the femora are larger relative to the body and wing than in the gregaria adults. Intermediate morphologies occur in the transiens (transient stage) during the transformation from solitaria to gregaria or the reverse.

Figure 6.15 Flow diagram depicting the derivation of the “ecoclimatic index” (EI) as the product of population growth index and four stress indices. The EI value describes the climatic favorability of a given location for a given species. Comparison of EI values allows different locations to be assessed for their relative suitability to a particular species. (After Sutherst & Maywald 1985.)

Box 6.3

Figure 6.16 Modeled distribution for Austrochlus species (Diptera: Chironomidae) based on presence data. Black, predicted presence within 98% confidence limits; pale gray, within 95% confidence. (After Cranston et al )