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Under optimal conditions, adult firebrats moult about every 9 days (English strain) or 13 days (American strain), irrespective of age, sex, or reproductive activity. The epidermis is activated on the 4th or 5th day of the 9-day stadium and the deposition of the cuticle follows 2 days later. There is a critical period for the secretion of a brain hormone on the 5th or 6th day of a 13-day stadium, equivalent to the 3rd or 4th day of the 9-day stadium; maximal activity in the ventral gland coincides with or follows shortly after this, also coinciding with the activation of the epidermis. Thus the control of moulting in Thermobia closely resembles that in the pterygotes.

The female firebrat must mate before she can complete the terminal stages of vitellogenesis. Mating is followed by an increase in stainability of the median neurosecretory cells, and by increased rates of RNA and protein synthesis in these cells. The volume of the corpus allatum, corrected for differences in size among firebrats, increases approximately 70 per cent after mating due to an increase in cell number and to increase in the volumes of both nucleus and cytoplasm. Increased RNA and protein synthesis accompanies these changes in volume. Extirpation of the corpora allata, and the implantation of corpora allata from Periplaneta americana , confirm that these glands stimulate yolk deposition. The results also indicate that the corpora allata can regenerate, and that wounding, or premature initiation of the moulting cycle associated with it, can inhibit vitellogenesis.

Fertilized eggs ofHodotermes mossambicus took up water progressively during the last 15–16 days of the 24–25 day incubation period. Both the large eggs from founding pairs and the small eggs from mature colonies approximately doubled in weight. Infertile eggs, 50% of which survived for 14 days, showed a lower rate of water uptake.

Ovarian changes which accompany the changes in the rate of oviposition in founding females of Hodotermes mossambicus involve alterations in the number of ovarioles in which yolk deposition occurs, and in the proportion of oocytes which enter the final stage of maturation.

The female firebrat can mate from the first to the fifth day after ecdysis, but most mate between the first and third days. Mating initiates the deposition of proteinaceous yolk in the oocytes, oviposition following 2–4 days after mating. Thus, on the average, 4·69 days elapse between ecdysis and oviposition, with a standard error of 0·13 days, so that oviposition occurs almost exactly half-way through each adult stadium. The male also mates most actively during the first third of the stadium if exposed continuously to females, but the potential for full mating activity persists into the seventh day of the 9 day stadium in celibate males. The difference appears to depend on a finite capacity to produce spermatophores in any given stadium. As a result of these restricted mating periods, isolated pairs of firebrats can reproduce only if male and female moult within 3 or occasionally 4 days of each other.

The changes in three aspects of pair behaviour (aggressiveness, water drinking, and oviposition) were documented during the establishment of the incipient colony, and correlations among the changes were examined. Aggressiveness and water drinking appeared within 24 hr of pairing; the first eggs were laid 2 days later. Aggression reached a maximum about the ninth day, then declined; pair termites often evoked a hostile response from a group termite between days 5 and 15, but the aggression and response were not directly correlated. Increase in weight due to drinking reached a maximum between the fifth and seventh days. From the eleventh day to about the fifth week the weight fluctuated, but during this phase the intake and disgorgement of water were approximately equal; after it, drinking declined and the weight fell progressively to less than the initial weight. During this decline the offspring differentiated to functional workers and soldiers. The rate of egg laying showed two peaks, one between the fifth and seventh days, and the other shortly after hatching commenced. The first batch averaged about 80 eggs, and the total reached an average of 200 about the thirteenth week. The decline in the rate of oviposition after the second peak more or less paralleled the decrease in drinking. Although drinking and oviposition are very closely co-ordinated, neither initiates the other; and it is likely that they, with aggression, are under common, central control.

Groups of Hodotermes mossambicus reproductives exhibit social behaviour. Maintenance of this behaviour by an individual depends on frequent contact of its body by the antennae of other termites. The antennae of the recipient do not play a role. Pairs on the other hand exhibit antisocial behaviour. Development of pair behaviour occurs when antenna to body contact is reduced or absent. Furthermore, at least the proximal parts of the antennae are required for full development of pair behaviour. Pheromones are not implicated in the change from group to pair behaviour.

Under optimal conditions, reproduction does not affect the rate of growth in female Lepisodes. In unmated male and female firebrats, an increase of weight after ecdysis is associated with a single phase of feeding activity, which terminates near the middle of the instar, coincident with the reconstruction of the midgut epithelium. In mated females, a greater increase in weight accompanies a more intense first phase of feeding, and at oviposition a short second phase of feeding commences. The weight of food consumed in this second phase is closely correlated with the weight of eggs laid, and evidently compensates for loss of reserves at oviposition.

The water-sacs of Hodotermes mossambicus are specialized salivary reservoirs. The water that they store reaches them through the gut and haemolymph.