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SUMMARYThe moniliaceous fungus, Hirsutella thompsoniU grown on potato‐dextrose agar (PDA) or on sterile wheat bran, was highly pathogenic to the carmine spider mite, Tetranychus cinnabarinus, and, grown on PDA, to the oriental spider mite, Eutetranychus orientalis. The fungus penetrated the mites' integument mainly through the legs and formed hyphal bodies in chains in the haemolymph. Hyphae, on which the spores were produced, began to emerge through the genital and anal apertures and then all over the body. Various mycophagous mites, a predaceous species and the tick Argas persicus were immune. H. thompsonii grew well on cadavers of diverse insects and mites.The fungus killed most mites and quickest, usually by the 2nd day, at 25o, 27o and 30 oC; least at 13o and 35 oC. It sporulated best on mites at 24o, 27o and 30 oC (full sporulation at 27 oC took place within 12 h after death); it was good, but slower, at 13o and 35 oC. The fungus germinated, penetrated mites and sporulated there very poorly below 100% r.h. When the daily number of hours at 100% r.h. was reduced from 24 to 18 or 6 h, fungus‐associated mortality dropped greatly.In the field, use of the fungus for mite control would be suitable particularly in tropical and humid subtropical areas, and its success in Israel would not be assured. In glasshouses, H. thompsonii could induce epizootics in Israel and elsewhere only if humidities were raised to saturation and the daytime temperature kept below 37 oC.

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SUMMARY Daucus maximus, Ridolfia segetum and Caucalis tenella, members of the Umbelliferae, were found to be foliage hosts of naturally occurring Alternaria dauci in Israel. A. dauci was also isolated from Daucus maximus seed.When infected cultivated carrot petioles were stored dry for 3 months, A. dauci retained its ability to spore, which was lost, however, in alternating wet and dry conditions, an effect paralleled by the loss of mycelial viability in similar soil storage tests. A. dauci colonizing moribund foliage stayed viable longer when the foliage was on the surface than when buried in soil at depths of 10 and 20 cm.Viable thick‐walled hyphae of A. dauci were found in the inner pericarp layer of Japanese seeds from which infected seedlings developed.