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1. Pollen on stigmas and the bodies of honey-bees foraging on almond blossoms was identified in 1988 and 1989. The percentage of blossoms setting nuts also was measured with respect to a tree limb's adjacent pollen source. 2. Every honey-bee that we collected foraging on almond blossoms had selfpollen on its body and 90% or more had cross-pollen. In 1988, 60-92% of the foragers had non-almond pollen on their bodies, while in 1989 the percentages were 92-100%. 3. In 1988 there was significantly more selfand cross-pollen on foragers' bodies than non-almond pollen with the exception of 'Peerless' nectar collectors. However, in 1989 the percentages of crossand non-almond pollen were equivalent except for 'Price', and were significantly less than the percentages of self-pollen. 4. In 1988, 42-1-81-2% of the stigmas we examined had self-pollen, 36-8-68 7% had cross-pollen, and 43-7-94 0% had non-almond pollen. In 1989, 60 0-100 0% of the stigmas had self-pollen, 10-100% had cross-pollen, and 8O)0-100 0% had non-almond pollen. 5. The percentages of pollen types on stigmas did not differ significantly between limbs adjacent to trees of the same or different cultivars. In 1988 the percentages of selfand cross-pollen on stigmas were equivalent in all cultivars except 'NePlus' which had significantly more selfthan cross-pollen. In 1989 there was significantly more selfthan cross-pollen on stigmas of all cultivars except 'Price' which had equivalent amounts of both pollen types. In both years non-almond pollen occurred with equivalent or significantly higher frequencies than self-pollen. 6. Nut set on limbs adjacent to compatible pollen sources did not differ significantly from those within the same row adjacent to trees of the same cultivar (i.e. incompatible pollen sources). 7. The population of honey-bees capable of cross-pollination in almond orchards is apparently a majority of the overall honey-bee foraging population and is homogeneously distributed throughout the orchard.

The pollination phase in the reproduction of the monoecious Cnidoscolus texanus is primarily nocturnal: pollen and nectar production, peak fragrance emission, and most intense insect visitation to the blossoms all commence with dusk and conclude at dawn. The two principal visitors, the night foraging hawkmoths Hyles lineata and Manduca quinquemaculata, visit both the carpellate and staminate flowers for nectar and carry copious quantities of pollen on their proboscises. Although the plant species is self-compatible, the pattern of flowering for each plant essentially precludes self-fertilization. Therefore the primary mode of reproduction in Cnidoscolus is sphingophilous outcrossing. Bull nettle, Cnidoscolus texanus (Muel. Arg.) Small, is a common plant of sandy wastelands in south-central USA and north-central Mexico. Its floral biology was investigated for three populations of abandoned fields near The University of Oklahoma Biological Station, 2 mi E of Willis, Marshall County, Oklahoma over the summer of 1972. Cnidoscolus texanus, is monoecious with the flowers borne in numerous, terminal cymes. Each cyme includes one, very rarely zero or three, carpellate flowers subtended by 6-12, typically 9, staminate ones. The perianth is 5-lobed and corollalike, and in the staminate flowers, united to form a trumpet blossom (Faegri and van der Pijl 1971) with a tube 14-20 mm deep and a limb of five free lobes 10-16 mm long. The 10 stamens typically are arranged in two numerically equal but morphologically dissimilar and distinct series. The filaments of the inner whorl are basally coalescent and their anthers extend only to the mid-level of the perianth tube. Stamens of the outer whorl are free with the anthers slightly exserted. Occasional plants differ with respect to the numerical distribution of anthers between the series; a few are monadelphous; and finally in some, the central anthers are exserted and the outer series shorter.

Bees, like their wasp relatives, forage for and transport food to a nest as provisions for their offspring. Unlike female Sphecoidea which transport arthropods one at a time as prey, bees transport pollen requiring specialized scopal (brush) or corbicular (fringed plate) structures to transport the dustlike material externally. Scopae often exhibit further modifications in density and amount of plumosity in relation to the size and ornamentation of the pollen grains they transport. Bees also differ from sphecid wasps by possessing branched body hairs that are relatively densely packed. These hairs, the electrostatic surface potential, and specialized hair groups for extraction of hidden pollen are important in the acquisition of pollen from flowers. Structures for grooming (brushes, combs, and scrapers) and grooming behavior patterns are modified to permit manipulation and packing of pollen in the specialized transport structures. The addition of nectar, so that pollen is packed moist, is a behavior that permits the carrying of pollen of a great variety of sizes and ornamentations in relatively simplified scopae or in corbiculae. The addition of oils to the diet of some bees has resulted in a modified type of scopal structure that has a wooly area basally and stiff guard hairs extending distally and that can transport a mixture of oil and pollen. Special hairs on the fore and mid basitarsi and teeth of hind tibial spurs are modified as oil scraper and manipulation structures. The use of corbiculae in Apidae to transport nesting materials and the hind tibiae in male orchid bees (Euglossini: Apidae) for transporting aromatic compounds involves behavior patterns similar to those for pollen transport in grooming, manipulating, and packing the materials. Other behavioral and physiological adaptations important in the location and acquisition of pollen by bees include individual constancy, oligolecty, seasonal synchrony, preimaginal conditioning, daily synchrony, buzz pollination, and other responses to specific modes of pollen presentation. Most of the behavioral patterns involve learning. They may be modified by extrinsic factors, and they may modify intrinsic structural and physiological characters.

Melecta separata callura (Cockerell), the primary biotic enemy of Anthophora edwardsii Cresson, behaves similarly to its European congeners, but differently from other North American parasitic melectine and nomadine bees. Features unique to Melecta (s. str.) include: digging through the soil plug of the completed host burrow; opening a small hole in the cap of the cell; ovipositing through this opening and attaching its egg to the roof or upper cell wall; resealing the cell; and replugging the host burrow. The bees spin a cocoon. They pupate in the autumn and overwinter as adults in the cells of their hosts. Melecta was parasitized by Sphaeropthalma unicolor (Cresson) and an undetermined bomblyiid fly. With the exception of a few host associations and flower records, there have been no studies on the ecology and behavior of any North American species of Melecta. Some features of the life history and interrelationships with host species have been worked out for the related Xeromelecta californica (Cresson) by Linsley and MacSwain (1942) and Porter (1951). These studies serve as a useful basis for comparisons between the two genera. In addition, a few studies on the ecology and behavior of European species of Melecta M. armata Panzer by Semichon (1904, 1911, 1922, 1925) and Malyshev (1928) and M. luctuosa Scopoli by Giordani-Soika (1936) provide a basis for intrageneric comparisons. Melecta (Melecta) separata callura (Cockerell) is a parasite of Anthophora edwardsii Cresson. The present study was conducted at a site near Coalinga and is; supplemented by unpublished 1947 observations made at a site near Somersville by Drs. E. G. Linsley, J. W. MacSwain and R. F. Smith. Thorp (1969) has discussed the ecology of the host bee, the habitats of the two sites where M. separata was studied, the temporal and spatial distribution of the two species, and has briefly outlined the ecology of the parasite. The present paper treats in more detail the behavior of the adult females. associated with oviposition, and the feeding behavior and development of the larvae of