The transmission of Theileria parva by nymphal and adult Rhipicephalus appendiculatus was compared by the assessment of salivary gland infections in tick batches fed on the same group of infected cattle at the same time. When larval and nymphal R. appendiculatus Muguga ticks were fed concurrently on cattle undergoing acute infection with T. parva Muguga, the resultant nymphae developed a slightly lower prevalence of infection than did the adult ticks. The abundance of infection was 5–20 times higher in the adult ticks than in the nymphae. When larval and nymphal R. appendiculatus Muguga and R. appendiculatus McIlwaine were fed to repletion on cattle infected with T. parva Boleni, a parasite causing subacute infection, resultant adult tick batches had a relatively high prevalence of infection, but infection was not detected in resultant nymphal batches. When cattle that were carriers of 2 stocks of T. parva, Marikebuni and Kiambu 5, were used as the source of infection, the infections developing in adult R. appendiculatus Muguga ticks were much higher than those developing in nymphae. The structure of salivary glands differed between nymphal ticks, adult males and adult females, and this is considered to be an important factor affecting the infection levels. The morphology of the type III acini, the target acini for sporogony, was similar, but the mean numbers of type III acini were different, with 87 in nymphae, 1346 in males and 1736 in females. This difference was correlated with the different infection levels produced in the various instars and sexes. While the process of sporogony in the different tick instars and sexes was similar, the rate of sporogony was fastest in feeding nymphae, taking on average 2–3 days, compared to 3–4 days in females and an irregular period in the males. These results are discussed in relation to the epidemiology of T. parva.

Investigations on the biology of Cinara cupressi, a voracious aphid of cypress trees in Kenya, showed that the aphid produced four nymphal instars within a fortnight under laboratory conditions of 22°C and 89% r.h. Reproduction was two nymphs per female adult per day for 12 days of reproduction. Nymphal multiplication was brisk, but was drastically countered by mortality which was highest in the first, third and fourth instars. This led to a mere nymphal survival of 11.0% at most under laboratory conditions.

The biology of Thrips nigropilosus Uzel was studied in a laboratory. The life history was examined at 20°C as well as the effect of temperatures on its life cycle at 12, 20, 25 and 30°C with fixed 70% r.h. The thrips pass through egg, two larval instars, prepupae and pupae to become adults. The development of these pre-adults occur on the pyrethrum plants except that prepupal and pupal stages occur in the soil. The emerged adults display sexual dimorphism, with lower ratio of male to female (2:11) and adult longevity range of 1–21 days.

The thrips development duration decreased with increasing temperatures. When expressed as rates, it was found out that faster development occurred for the second larval and pupal instars than other stages with an increase in temperature. The optimum temperature for the thrips development was 20°C, mortality being higher at other temperatures.

Laboratory studies were carried out to determine the effect of high larval densities of Plodia interpunctella (Hubner) on the development and survival of the moth in two food media. Mortality was found to be higher when reared on groundnuts than on artificial diet. Mortality was between 6.6 and 13.3% when larval densities were below five larvae on 3 g of both groundnuts and the artificial diet in 75 × 25 mm tubes. At higher larval densities (10 or more larvae on 3 g of medium) mortality ranged from 22.5 to 60% on the artificial diet, and on groundnuts it was between 30 and 65%. In both media, development period was prolonged and weights of moths at emergence was lower when larval densities were greater than 10 per tube.

When high densities were experienced between the first and the fourth instars individuals had protracted development, high mortality at larval stage and reduced weights of emerged adults and those subjected to high densities only at the final instars were less significantly affected. It seems that the fourth larval instar is the stage most sensitive to high densities.

Four instars of Cerataphis palmae (Ghesquierei) ( = Cerataphis variabilis H.R.L.) were identified from laboratory-bred and field-collected alatoid and apterous immatures through morphometric studies. These were distinguished most readily by the number and shape of antennal segments, body size, degree of development of the thorax, the presence or absence of wing pads and crenulations on body margin.

The onset of oviposition, incubation period, instar duration and polymorphism in the first progeny of Macrotermes michaeheni were investigated. Most incipient colonies have their first batch of eggs within the first week following establishment of the colonies. The incubation period for these eggs was 36.2 days. Three male and female larval instars, minor and major workers, and minor soldiers were found in the first progeny. Neither fourth instar larvae, which subsequently moult into major soldiers, nor nymphs, which develop into reproductives, were detected.

The duration of each larval instar was determined. The longest duration was that of third instar larvae developing into both minor and major workers. The first neuter terminal castes which appeared in the colonies were minor workers, followed by major workers and, soon after, by minor soldiers in the majority of cases.