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Uvarov (1928) lists a number of records of species of Trichodes occurring as predators of the eggs of Dociostaurus maroccanus, including T. amnios F., T. umbellatarum Ol. and T. laminates Chevr.

T. laminatus has been reported as an egg-predator of Dociostaurus in Iraq by Jackson (1926) and Bodenheimer (1944) and I have myself seen it in egg-pod samples from the Syrian Djezireh. Waterston (in Uvarov et al., 1951) recorded it from Cyprus and made some observations on its distribution in the island. He commented upon the synchronisation of the emergence of adult beetles with the appearance of fledgling locusts. He also noted that the flowers of Teucrium polium had a marked attraction for Trichodes adults and some Bombyliids and suggested that the flowers of certain plants might serve to retain the adult predators on the site until the locusts were mature and had begun to lay their eggs. This has since been confirmed.

Trichodes laminatus is a metallic green beetle with yellow markings on the elytra (Fig. 20). It closely resembles T. amnios (figured by Künckel, 1893-1905, p. 616) and T. umbellatarum. The males have the same markings and are the same size as the females (the average length, measured from the front margin of the thorax to the hind tip of the elytra, of 28 males and that of 17 females, was 9-6 mm.) but the males are easily distinguished by the greatly enlarged hind tibiae.

Fig. 20.-Adult female Trichodes laminatus Chevr. var. cyprius Reitt.; the right hind leg is that of the male.

Trichodes is to be found in many, but not all, of the sites in which Dociostaurus occurs in Cyprus. Adults are very difficult to find where there are locust populations of permanently low density, and only isolated individuals have been found where there are no locusts, suggesting that Trichodes larvae are almost confined to the egg-pods of Dociostaurus. Comparatively few pods of other Acridids have been examined, but one of Calliptamus barbarus containing a fully fed Trichodes larva was found in an egg-pod sample collected at Akhna on 3.II.54. This, however, is probably not a common occurrence. A Trichodes larva will eat the contents of two Dociostaurus egg-pods if it has the chance, as for example when two pods are laid side by side adpressed to one another, and in such a case will grow considerably larger than normal and produce larger adults. The pod of Calliptamus has more and larger eggs than that of Dociostaurus, yet very few abnormally large Trichodes adults have been found. Moreover, the structure of the Calliptamus pod, with a soft froth plug partially projecting or flush with the soil surface, is very different from that of Dociostaurus. Of the other common Acridids on the sites, Oedipoda miniata lays a very small oval pod, quite distinct in structure. There can be no doubt that Trichodes principally attacks Dociostaurus pods and only rarely those of other species.

The adult beetles emerge at the beginning of May and are honey- and pollen-feeders. Their emergence coincides with remarkable regularity not only with the fledging of adults of Dociostaurus but also with the general opening of the flowers of Teucrium polium (Table 29).

Table 29 The relation between the dates of the first appearance of Trichodes adults, Teucrium flowers and Dociostaurus adults. (The date on which Trichodes adults were first seen in 1951 was probably a little later than the date of the first emergence on the site, since they were not specifically sought earlier than this)

For the first week or two of adult life, Teucrium is the principal food-plant on most sites. There are few other plants in flower at the time and of those that are, none are common. However, Trichodes does occasionally feed on Centaurea hyalolepis, Onopordon tauricum and Asteriscus aquaticus and at Sotira Centaurea is sometimes one of the principal food-plants (Table 30). This plant is abundant on the abandoned and fallow fields that traverse the site, although it does not occur on the undisturbed land around. Ammi majus and one or two other umbellifers are also much frequented. Nevertheless, Teucrium is the most widespread of these plants on locust sites, and where there is a choice it appears to be preferred. A fortnight or so after the emergence of the adults Eryngium creticum comes into flower and replaces Teucrium, which it outlasts, as the principal food-plant.

Table 30 The numbers of Trichodes adults caught in 100 sweeps (200 in D) and the vegetation of different sections at Sotira site in 1953

Vegetation of the various sections on 12.v.53:
A - Dry Stipa A grassland
B₂ - Abundant Centaurea hyalolepis and other flowering thistles
B₃ - Sparse Centaurea hyalolepis
C₁ - Occasional Centaurea and Chrysanthemum coronarium
C₂ - Rather dry but abundant Centaurea
D - Kafkalla vegetation: Stipa A and B grassland. Teucrium not uncommon
E - Occasional Centaurea and Eryngium

Teucrium polium L. (Labiatae) is a low woody perennial, forming compact cushions up to 10 inches across, of densely crowded, leafy branches, each terminating in a head of flowers which open in succession over a period of about a month. It is not uncommon on locust sites as a constituent of the phrygana, though locally absent, but it is not confined to them. Where it occurs it is usually found near rocky outcrops.

Eryngium creticum Lam. (Umbelliferae) is a summer-flowering annual or short-lived perennial. The abundance of flowering stems produced even by those plants which survive more than one year is markedly affected by fluctuations in the winter rainfall. In a very dry season few plants flower. Thus, in its behaviour it resembles a summer-flowering annual. It is rather frequent on heavily grazed pastures in the lowlands, especially on deep soils, but rare on some kafkalla sites. Like Teucrium, Eryngium has heads of small flowers which open in succession over a long period.

The adult Trichodes are very active in sunlight, feeding and flying from plant to plant. When a cloud passes over the sun, or if there is a strong cool wind, they burrow among the stems of the Teucrium bushes or hang under the heads of Eryngium and remain motionless. They appear to spend the night in a similar manner or clinging to the undersides of the branches of dead thistle stems, etc. When disturbed, they usually fly away at once; if surprised, they may drop to the ground and behave as if dead, but after a few seconds they pick themselves up, run along the ground for a foot or two, climb a stem and take off. They show no sign of being attracted either to adult Dociostaurus or to locust egg-pods.

Sample counts of adults were made at irregular intervals but as far as possible at the same time of day and under more or less the same weather conditions, i.e. full sun and light wind. Two counts were recorded: those found in a search of the site for a fixed period of time, usually an hour, and those collected in a fixed number of sweeps throughout the site. The numbers of Trichodes caught in the course of sweeping for Dociostaurus were recorded for Sotira, Akhna and Mia Milea in 1952 and for Sotira and Akhna in 1953. No sampling of Dociostaurus by sweeps was carried out at Mia Milea in 1953, so separate sweeps were made for Trichodes. In 1952, some counts of numbers caught in half-hour searches were recorded from the "Trichodes site" at Mia Milea, and in 1953, this method was widely used, counts being made at Akhna, Sotira and all three sites at Mia Milea, for comparison with those obtained by sweeping. In 1954, sweeping was abandoned and only the second method used. More frequent counts were made on the Mia Milea sub-sites and very few elsewhere. In general, the two methods gave similar results, but searches were preferable for several reasons, one being that the beetles were not so likely to be damaged during collection and so could be marked and released with less danger of mortality through handling. The results are shown graphically in Figs. 21-24.

Fig 21. - The number of Trichodes in samples catches at Akhna, 1959, 1952. The number of sweeps varied between 400 and 550, but the numbers of Trichodes caught have been adjusted to a standard of 550, this being the number of sweeps in most of the samples.

Fig. 22 - The numbers of Trichodes in sample catches at Akhna and Sotira, 1953.

The population changes were very regular in the samples from Akhna and Sotira (Figs. 21 and 22). There was a short period of emergence, a peak of maximum numbers and a long fall-off. Only at Mia Milea was there considerable variation (Figs. 23 and 24). The reason for this appeared to lie in the nature of the site. At Akhna and Sotira both the locust and the Trichodes populations are rather isolated, but at Mia Milea there is a more or less continuous distribution of Dociostaurus and Trichodes over a large tract of country. The sub-sites chosen for study at Mia Milea can be delimited geographically, and in the absence of large-scale movements, the populations can be treated as reasonably well-defined units. The upper and lower sites are separated by several hundred yards, including a river bed in which locusts are not found. Yet it is possible to walk for miles in either direction over similar rough grazing on which Dociostaurus is widely though unevenly distributed. The terrain is hilly and the vegetation varied. Teucrium and Eryngium are both widespread and Trichodes can usually be found where they occur. There is thus the possibility of immigration from outside into the areas sampled. Moreover, at Mia Milea two (or three) sub-sites were sampled and changes in population distribution can be traced which would not be apparent if only a single sub-site had been sampled.

Fig. 23 - The numbers of Trichodes in sample catches at Mia Milea, 1953.

Fig. 24.-The numbers of Trichodes caught in one-hourly collections at Mia Milea, 1954. The latest date for the entry of Trichodes larvae into egg-pods (upper site data) was July 17th.

The distribution of adult Trichodes appeared to be related to the distribution of their food-plants. Teucrium is rather abundant on the "Trichodes site", less so on the lower site proper and uncommon on the upper site, except for a narrow belt at the extreme north of the sampling area. In 1951, a semi-drought year, few summer annuals survived to flower and Eryngium flowers were rare; consequently, Teucrium was almost the only food-plant, and as will be seen from Table 29, Trichodes disappeared early.

The winter of 1951-1952 was wet and the growing season long. Many species of plant remained in flower unusually late. However, little seed had been set by the summer annuals in 1951, and in 1952 Eryngium, though not rare, was not as common as it subsequently became. Teucrium was probably the principal food plant at Mia Milea. In the egg-pod samples collected in the late summer of 1952 (July-September), the percentage of pods attacked by Trichodes varied directly with the abundance of Teucrium on the three sub-sites, viz. Upper site, 9.1; Lower site, 15.7; "Trichodes site", 39.0. This reflected the relative abundance of Trichodes adults; no numerical data are available, but the "Trichodes site" was so named because of the abundance of adults there that summer. Nor are there numerical estimates of the relative abundance of the food-plants in 1952, but in 1953, estimates were obtained from counts of plants in 10-sq. ft. wire squares laid at random on the three sub-sites. The counts were made with a slightly different purpose in view than direct comparison, and the figure for Teucrium on the lower site is certainly too low since the hollow, on the border of which most of the Teucrium on this site occurs, was not sampled. The figures are as follows:

In 1953, Eryngium was common on the upper site, and in 1954, it was still in considerable quantity. Estimates of the total number of flowering plants in the area were 4,900 in 1953 and 2,400 in 1954. In 1953, the Teucrium on the "Trichodes site" and lower site scarcely flowered because the flowering heads were eaten by Calliptamus hoppers which were rather abundant that year. Eryngium was thus the principal food-plant. The flowering periods of Eryngium and Teucrium for 1953 and 1954 are given in Figs. 23 and 24.

It will be seen that in 1954 the peak numbers of Trichodes adults occurred on the lower site before they occurred on the upper. The coincidence of the onset of flowering of Eryngium and the rise in numbers of Trichodes on the upper site is striking, and suggests that the increase was due to a concentration of adult beetles on a new food source. This suggestion is borne out by certain figures obtained from the recapture of marked individuals. The marking and release of Trichodes was carried out throughout the 1953 and 1954 seasons; it will be discussed below (p. 93). Meanwhile, the details of all the Trichodes that were marked and released on one sub-site at Mia Milea and recaptured on another during 1954 are given in Table 31. There were few, but those recorded support the idea that there was early concentration on the Teucrium on the lower site, followed by movement towards the upper site as Eryngium replaced Teucrium as the principal food-plant.

Table 31 Dates of release of marked Trichodes on one sub-site at Mia Milea and their recapture on another during 1954. (L.S., lower site; U.S., upper site; T.S., Trichodes site)

Trichodes continued to be found on the lower site and the "Trichodes site" in some numbers until the end of the season, feeding on Eryngium. That the actual number of adults captured on the upper site was greater than that from the lower sites at this time is probably because the area searched on the upper site was larger.

The early peak was scarcely marked in 1953, partly because of the failure of the Teucrium to flower properly, but the situation was complex. Rain is rare at this time of year, but on the night of the 29th May there was a heavy local storm. This was followed by a rapid increase in numbers on the upper site, suggesting a causative relationship, i.e. that rain may stimulate emergence, or that very dry ground may hinder it. It is noteworthy that Trichodes larvae kept in soil in the laboratory will not pupate unless the soil has previously been moistened. The presence of water after the temperature has risen above a certain level may be essential for pupation.

In Table 32, the relation is shown between the numbers of locusts, the numbers of adult Trichodes and the percentage predation rate at Akhna over the years 1951-1954. Akhna was a typical grazed kafkalla site until about 1950, when it was closed to grazing and subsequently planted with wattle (Acacia cyanophylla). Under protection, the percentage cover and the height and luxuriance of the vegetation increased. Latterly tall grasses have begun to invade the area and the wattle is forming a shrub cover. It has become an unfavourable habitat for Dociostaurus, as is shown by the steady fall in numbers since 1952. But during 1952-1954, at least, there was abundant food for Trichodes adults, which were numerous on the site in 1952 and 1954. The percentage predation has steadily increased although the actual numbers of Trichodes larvae may have decreased. The figures suggest not only that changes which favour Trichodes may be unfavourable to Dociostaurus, but also that an increase in the egg-predation rate may reinforce other factors in reducing locust numbers when grazing ceases.

Table 32 The relation between the numbers of locusts, the numbers of Trichodes adults and the percentage Trichodes predation at Akhna. (The number of sweeps for which Trichodes adults were recorded is 550. The estimates of locust numbers cannot be made more precise)

The sex ratio among the Trichodes caught in the regular sampling was not unity. The figures for two years at Mia Milea (all sites) are as follows:

he preponderance of males was maintained more or less throughout the season. The more scanty data from Akhna and Sotira are as follows:

The number caught at Sotira is too small for the difference in sex ratio to be significant, but taking all collections together there is a small but real excess of males over females. One possible explanation is that ovipositing females were overlooked in the searches and missed in sweeping, being at ground level.

In 1953 and 1954, at irregular intervals throughout the season, batches of Trichodes adults were marked with artist's oil paint on the elytra and were released, principally at Mia Milea. Separate marks were used for different sites and for each day's marking. The object of marking was primarily to obtain an estimate of the length of life of the adults and, if possible, information on their movements. In addition, some estimates of population numbers were made.

In 1953, 273 Trichodes were marked at Mia Milea and of these, 27 were recaptured, 7 on the day of release and 20 subsequently. In 1954, 1,058 were marked and 38 recaptured, one on the day of release and 37 subsequently. These totals include two attempts to estimate actual as opposed to relative numbers on the site, by the marking and recapture method. In 1953, 32 were marked and 7 recaptured on 5th June, and in 1954, 159 were marked on 28th May and 10 recaptured on the following day. Excluding these two special marking experiments, the percentage recovery in 1954 was much smaller than in 1953. This can be explained partly by the fact that many hundreds were marked late in the 1954 season, when their chances of recapture were small, and partly by the higher total numbers on the site in the latter year.

Details of the recaptures are given in Table 33. The maximum time that elapsed between recaptures in 1953 was 14 days for both males and females. In. 1954, the time was 28 days for a male (4.v.-l.vi) and only 9 for a female (4.v.-13.v). Ovary examinations suggest, however, that the life of the female can be at least 28 days, and is probably much more (see p. 96).

Table 33 Recaptures of marked Trichodes at Mia Milea, 1953. (Those recaptured on the day of release are not included) 1953

From time to time the country immediately around the sites at Mia Milea was searched for marked adults but only one was ever found out of nearly 500 examined and that one was less than 100 yards from the lower site. The number marked was of course small in proportion to the total population of the areas. The maximum distance over which an adult is known to have travelled is thus the distance between the two sites, a maximum of some 700 to 800 yards.

On one occasion in 1954, a deliberate attempt was made to estimate the numbers of Trichodes adults by the marking and recapture method. From the recaptures of adults marked on other occasions estimates could be made when the number of marked recaptures was more than one, and the time elapsing between release and recapture small: These estimates are given in Table 34.

Table 34 Population estimates from the marking and recapture of Trichodes at Mia Milea

Of these estimates, the last is probably the best, but it is unlikely to be good because the numbers marked were small, and no allowances were made for mortality or emigration. They are, moreover, only estimates of the numbers on the site on a particular day, in both cases a little before peak numbers were reached. Nevertheless, they give an idea of the order of the difference in size of the populations between the two years. Dempster (1957) gives estimates of the total numbers of Trichodes larvae on the upper site based on estimates of the total number of egg-pods and the percentage predation. These have been modified by substracting the percentage known to have suffered superpredation, etc. (except for 1952 for which this is not known) and are given in Table 35, together with the two estimates of adult numbers on the upper site.

Table 35 Estimates of the numbers of Trichodes larvae and adults on the Upper Site at Mia Milea. (The estimates of the numbers of adults are estimates of the numbers on the site on particular days only)

The relation between the estimated numbers of adults and the estimated numbers of larvae that occurred subsequently is acceptable on the assumption that the adults found on the site are the parents of the larvae, but the relation between the numbers of larvae and the numbers of adults appearing on the site in the following year is only understandable if there are considerable population movements in and out of the area.

Unfortunately, the data were not adequate for analysis by more sensitive methods.

Trichodes adults were seen mating on Teucrium bushes about a week after they first appeared. Oviposition was never observed in the field, but in cages in the laboratory the beetles lay in cracks in the soil, depositing eggs singly or in clusters of up to 20 at a time 5 to 10 mm. below the surface. The extruded ovipositor is inserted into rather fine cracks and may perhaps even penetrate uncracked soil. It possesses several strong terminal bristles which may possibly be used for boring. Eggs have only once been found in the field, in spite of prolonged searching; five were found in cracked soil among short open vegetation on the lower site at Mia Milea.

The paired ovaries have from 15 to 30 ovarioles in all. Four to five eggs can be matured in a single ovariole in the course of a season, and the maximum number of eggs laid is probably between 100 and 150. Maturation is ;slightly irregular. After ovulation the eggs lie in a chamber formed by an enlargement of the upper end of the oviduct for a period before passing into the vagina.

Stages of development of the ovary were distinguished, their characteristics being as follows:

A small round, orange-coloured mass of tissue (corpus luteum) may appear at the base of the ovariole, usually after the third ovulation. It probably results from the degeneration of the follicle of the first egg, but it is not invariably present, the empty follicles often remaining white and very little shrunken. Two corpora lutea have not been seen in an ovariole. It is possible that several follicles degenerate to form a single corpus luteum.

Samples of female Trichodes were collected at intervals during May and June, 1952 from the main sites, for dissection and examination. The numbers of individuals and the stage of development of their ovaries are shown in Table 36. The data suggest that there is a short period of emergence; early stages of ovary development were not found late in the period of occurrence of adults. The three females with Stage II.2 ovaries collected at Sotira on 5.vi had ill-defined corpora lutea and should probably be regarded as at Stage IV. 2. Judging from these figures, the maximum length of life appears to be a little more than a month.

Table 36 The numbers of individuals and the stages of ovary development of adult Trichodes collected at Akhna and Sotira in May and early June, 1952. (The figures for Sotira are underlined)

Few Trichodes were examined from Mia Milea; the data are not included in Table 36, but they are comparable with those obtained from the other two sites. There is no evidence to suggest that the emergence period was exceptionally prolonged at Mia Milea in 1952 or 1954. On the other hand, the results of the few examinations of ovaries in females collected there in 1953 suggest that there was more than one period of emergence, as does the evidence from sample counts (p. 91). The data are as follows:

(Trichodes was first seen on all sites on 4-5.v.)

The eggs are shown in Fig. 25. They axe approximately 2.2 mm. long and 0.6 mm. in maximum diameter, smooth, unsculptured and pink. This pink coloration occurs in all stages of the life-history of the species; the larvae are pink even their frass is pink, and many tissues in the adult are pink. On the open bench in an unheated laboratory in Cyprus, the eggs hatched in 10 to 14 days, and judging from the time elapsing between the first appearance of Trichodes adults and the first appearance of infested pods, which was about 20 days, the incubation period is similar in the field.

Fig. 25 - Trichodes laminatus Chevr. var. cyprius Reitt. A, Eggs. B, first-instar larva, dorsal view. C, first-instar larva, right prothoracic leg. D, fourth-instar larva, dorsal view.

The newly-hatched larva is 3 mm. long (see Fig. 25) and intensely active from the moment of hatching. In the field, it has been found actively running over the surface of bare ground but only in the early morning and late afternoon. Probably it retreats into cracks in the soil during the hottest part of the day. It burrows into loose soil. When Dociostaurus egg-pods are laid, the top of the pod lies at the base of a small pit 2 or 3 mm. deep. This pit is filled with loose soil by the female after laying, and drifted over by wind. When the Trichodes larva comes to such a place it burrows in and applies itself closely to the pod, usually at the rather thin section immediately below the lid, but sometimes in the middle of the lid itself. The lower part of the pod is embedded in firmer soil and entry is not made here. The larva immediately begins to bite a small hole in the wall, and enters the pod through it, burrowing down through the froth to feed on the uppermost eggs. In pods attacked late in the season, the larva may travel further down into the pod before feeding, possibly reacting to higher soil temperatures, but by doing so it appears to lower its chances of survival, since the rather fluid contents of the eggs damaged during its passage may swamp it. Usually it retreats into its cavity in the froth when not feeding.

In the laboratory, these free-living first-instar larvae can survive for ten days or so, apparently without feeding. This is probably the case in the field also, since there is about a month between the disappearance of Trichodes adults and the appearance of the latest infestations, and the eggs may take about 14 days to hatch.

In 1952, two attempts were made to infest Dociostaurus egg-pods experimentally in the laboratory, using pods laid in cages and therefore free from predators. At the first attempt, set up on 23.v, one egg-pod was placed on the surface of some dry soil in a Petri dish and two Trichodes eggs, laid in the laboratory, were placed beside it. By 3.vi the eggs had died and three Trichodes larvae recently hatched in the laboratory were added. Eleven days later, on 14.vi the larvae could not be seen but when the pod was opened it was found not to be attacked.

In the second attempt, set up on 24.v, the pod was partially buried in loose soil. One first-instar Trichodes larva found in the field at Akhna was added. On 14.VI the pod was opened and a mature Trichodes larva found inside. No more laboratory egg-pods were available so the attempt was not repeated, but experimental infestation had been shown to be possible.

The first-instar larva feeds for some time before moulting. Feeding is more or less continuous between moults and the larva passes through a series of instars, very much resembling one another, although the eyes, limbs and anal cerci decrease proportionately in size with successive moults.

There appear to be four larval instars, or five if the larvae are kept in the laboratory and do not pupate. Of these, Instars I (free-living) and IV (fully grown) are figured (Fig. 25). When all the eggs are consumed the larva remains in the base of the pod. The time elapsing between the initial entry and the attainment of maximum size can be estimated from the time between the first appearance in the egg-pod samples of a very young larva in a pod and the first appearance of a fully-grown one with no host eggs left. The variation in this depends primarily on the variation in the number of eggs per pod since the larva eats all of them. The available data are as follows:

The total period over which infestation took place is the time elapsing between the first and last appearances of very young larvae in egg-pods. For 1952, the only year in which frequent samples were made throughout the summer, the available figures are as follows:

More frequent sampling would probably have lengthened this period to 8 or 8.5 weeks. It depends principally on the length of life of the adult beetles.

Multiple infection is not uncommon, but it frequently results in the death of the larvae soon after entry, possibly by release of too much of the fluid contents of the eggs. As many as nine dead larvae have been found in a single pod in June samplings. Such infestations are often followed by drying of many of the eggs or by fungal attack. When the larva is fully grown there is never more than one per pod, although two living half-grown larvae are not infrequently found earlier which suggests that cannibalism occurs. Double infection by Trichodes and Systoechus larvae is also found in the early stages but not in the later. It is more likely that the Trichodes eats the Systoechus than vice versa, because the Bombyliid, with sucking mouth-parts, merely sucks the juices and leaves the shells of the eggs; however, more importantly, multiple infection by Systoechus results in pods with two or three fully grown larvae, suggesting that here at least there is no cannibalism.

When fully fed, the larva, which until now has been head downwards, turns round in the pod until its head is upwards, pushes the frass up into the top end of the pod and secretes a diaphragm of threads spun from glands in its mouth. These threads, golden-yellow at first but darkening to dark brown, cement together to form a thin, tough, pliable membrane. Below the diaphragm, the wall of the pod is lined in the same way. Occasionally a second diaphragm is built immediately below the first. Having completed its cell in the lower part of the pod, not later than the beginning of August, the larva remains quiescent until the following spring, but its capacity for secreting this material persists and if the pod is damaged the larva repairs the hole. It pupates in April or May.

In the laboratory, larvae in pods have been kept, quite dry, for as long as three years without pupation. Such larvae can be induced to pupate and emerge by wetting the soil and keeping the cage heated. One such larva collected in the field in November, 1951 was treated in this manner and an adult female emerged on 11.v.54. It was, however, small, being just under 7 mm. long as compared with the average female length of c. 9.6 mm. Similar small adults have been encountered in the field, although rarely. When removed from the pod, the larva soon dies.

The pupal stage lasts a few days only; exactly how long is not known. The adult emerges from the pod by eating its way through the diaphragm and pushing aside the lid. There are always some adults that are unable to emerge from the pod. Usually the reason for this, as in the case of Dociostaurus hoppers at hatching, is that winter rains have deposited soil and buried the pod too deep.

A synopsis of the life-history is given in Table 37.

Table 37 Synopsis of the life-history of Trichodes

Dempster (1957) has discussed the importance of Trichodes attack in reducing the numbers of locusts at Mia Milea. Losses due to Trichodes are often very high locally, but it is doubtful if rapid increases in locust numbers can be appreciably and consistently reduced. While it is true that an increase in the number of locust egg-pods will increase the chances of a Trichodes larva finding one, Trichodes has only one generation a year and cannot therefore build up a high population in the event of an unusually large number of egg-pods being available. Moreover, the number of free-living Trichodes larvae must be related to the number of adult females on the site, which in turn is related to the abundance and distribution of their food plants. Circumstances that favour an abundant supply of food for the adults may not be those that favour an increase in locusts, as the figures for Akhna show. Thus, it is very unlikely that the Trichodes predation rate will vary consistently with the numbers of locusts; in fact, we have seen that it does not. In general, it is probable that a cessation of grazing will lead, initially at least, to an increase in the Trichodes predation rate.

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