Robert B. Willey

ARE PARTHENOGENETIC AND RELATED BISEXUAL INSECTS EQUAL IN FERTILITY

CARSON, H. L., AND K. Y KANESHIRO. 1976. Drosophila of Hawaii: Systematics and ecological genetics. Ann. Rev. Ecol. Syst. 7:311-345. CRADDOCK, E. M. 1974. Reproductive relationships between homosequential species of Hawaiian Drosophila. Evolution 28:593-606. KANESHIRO, K. Y. 1976. Ethological isolation and phylogeny in the planitibia subgroup of Hawaiian Drosophila. Evolution 30:740-745. KANESHIRO, K. Y., AND F. C. VAL. 1977. Natural hybridization between a sympatric pair of Hawaiian Drosophila. Amer. Natur. 11:897902.

Visual and Acoustical Social Displays by the Grasshopper Arphia Conspersa (Orthoptera: Acrididae)

Many species of the Oedipodinae (band-wing grasshoppers) exhibit strikingly diverse social interactions invoking visual and acoustical communication between the sexes and between individuals of the same sex (Otte, 1968, 1969).

A GEOGRAPHICAL ANALYSIS OF QUANTITATIVE MORPHOLOGICAL VARIATION IN THE GRASSHOPPER ARPHIA CONSPERSA

The speckled rangeland grasshopper, Arphia conspersa Scudder (Acrididae; Oedipodinae) ranges from Alaska and northern Canada to northern Mexico, and from California to the central Great Plains (Strohecker et al., 1968; Vickery, 1967; Helfer, 1953). Its altitudinal range is also quite wide, being from less than 1,000 m above sea level to nearly 4,000 m in the southern portion of the range (Alexander and Hilliard, 1969). Over this entire area the animal is springbrooded, the actual time of adult emergence being dependent on the onset of spring and final melt of winter snow. The distribution pattern of A. conspersa within this extensive geographic and topographic range is highly discontinuous, owing to its narrow habitat preferences and distinctive behavior patterns (Alexander and Hilliard, 1969; Willey and Willey, 1967, 1969,1971). Ecologically, the species is limited to shortgrass prairies and forest or brushland openings, areas in which the animals primary food sources, narrow-leaved grasses, are found interspersed with numerous small spaces of bare ground which are necessary for the performance of courtship rituals. Hence, dense forest, tall grass meadows, and xeric scrubland are uninhabited by A. conspersa, while ecotonal habitats, such as roadside meadows and old logged areas, may be slowly colonized (Willey and Willey, 1971). Moderately grazed pastures can also support large populations. Within such a habitat structure, A. con-

The behavioural ecology of desert grasshoppers II. Communication in Trimerotropis agrestis

Abstract Courtship and male-to-male signals which prevent ipse-sexual courtship are described and illustrated audiospectrographically in Trimerotropis agrestis gracewileyae Tinkham. Some signals are silent, whereas others have an acoustical component produced by friction of a femoral ridge against the file-like stridulatory surface of the hind-wings. Leg movements which pass above the body expose the coral-red inner surfaces of the femora and the red tibiae, affording an additional visual stimulus. Certain captive males in a closely interacting group of males perform a drumming sound which is produced in some way by a low fluttering motion of the hind femora. This latter behaviour pattern was not observed in nature.

The behavioural ecology of desert grasshoppers I. Presumed sex-role reversal in flight displays of Trimerotropis agrestis

Abstract Several aspects of the adult behaviour of Trimerotropis agrestis gracewileyae (Tinkham 1960) have been analysed. Sound spectrograms of flight sounds have been illustrated and discussed. Males and females both produce distinct acoustic signals (crepitations) during spontaneous and socially induced flights and they can fly silently (with only a slight rustle of the wings) when disturbed. The flight display of sexually receptive females is significantly of greater amplitude than the usual crepitation of either sex, and although it was observed but once and was not recorded on tape, it is worthy of reporting. Although Tinkham in his description of the subspecies reported that females were the sole crepitators and, therefore, responsibility for initial pair formation has been reversed in this population, our observations during 3 years and four separate visits to the localities through the season indicate that Dr Tinkham may have observed the rarely heard virginal or, more probably, normal disturbance-induced flights of females during the early part of the adult season and at times of the day when males are least active in flights. In general, therefore, the flight signalling patterns of this subspecies do not differ in kind from those of other oedipodines.