Using regression analysis on data compiled from the literature, I compared relationships (forewing versus body length) of mayfly imagoes, as a measure of dispersal, between suborders (Schistonota and Pannota) and among habitat type (lotic, lentic, and mixed). There were no significant differences in slopes or intercepts of the regression lines between sexes. Forewing length changed less markedly with body size for species within the ancestral Schistonota than the Pannota. Regression lines for lake and river forms intersect at 7.85 mm (wing length) and 7.30 mm (body length). Small (body length < 7.3 mm) lentic mayflies have proportionately longer wings than small riverine forms. Large (body length > 7.3 mm) riverine mayflies have proportionately longer wings than lentic forms. Based on these relationships, small lake-dwelling mayflies and large riverine mayflies are best able to disperse. Mayfly species occurring in mixed (both rivers and lakes) habitats exhibited allometric relationships similar to mayflies restricted to rivers.

In view of the background of information on Bacillus popilliae Dutky (Beard, 1945) and the reported success of this bacterium in reducing populations of Popillia japonica Newm. (White and McCabe, 1950) and in view of the discovery of a similar bacterium attacking Odontria grubs in New Zealand (Dumbleton, 1945), a survey of microparasites and their possible pathogenicity in scarabaeid larvae was undertaken in Australia as a project supported by a Fulbright award.

The Nearctic species of the subgenus Anomophagus Reitter of the genus Rhizophagus Herbst are revised. Four taxa are recognized: R. brunneus brunneus Horn 1879, R. brunneus fenyesi Méquignon 1913a, R. pseudobrunneus sp.nov., and R. galbus sp.nov.

For the other Nearctic species of the genus, a diagnosis, a type material section, and distributional notes are provided. Two new taxa are described, R. minutus rotundicollis and R. pusillus. Seven specific names are treated as new junior synonyms, namely (with the valid name in parentheses): R. longiceps Casey 1916 and R. rectus Casey 1916 (= R. cylindricus LeConte 1866); R. minutus quadriguttatus Méquignon 1913b (= R. minutus minutus Mmnerheim 1853); R. remotus luteus Méquignon 1913b (= R. remotus LeConte 1866); R. sculpturatus horni Méquignon 1913b (= R. sculpturatus Mannerheim 1852); R. dimidiatus testaceus Méquignon 1913b and R. dimidiatus assimilis Méquignon 1913b (= R. dimidiatus Mannerheim 1843). The subgenera name Syringobidia Casey 1916 (type species: R. cylindricus LeConte 1866) is treated as a new junior subjective synonym of Rhizophagus s.str. A key to all Nearctic species of Rhizophagus is provided with distribution maps of the species.

Mixed colonies of adults of Lytta nuttalli Say and L. viridana Le Conte, and of L. cyanipennis (Le Conte) and nuttalli, and colonies containing only one of these three species have been seen in various parts of the Canadian prairies, usually in aggregations and most commonly near bodies of water. The flight period of nuttalli extends from early June to early August, of viridana from late May to late June, and of cyanipennis from mid-June to early July. The natural food plants of these three species are a variety of wild legumes, though they prefer certain cultivated legumes when present. Nuttalli and viridana will eat some non-leguminous plants, including species of Iris, Delphinium, and Brassica, and such crops as sugar beets, oats, barley, and wheat. In captivity, males and females of nuttalli and viridana mated more than once and females deposited more than one batch of eggs. Egg batches of nuttalli, viridana, and cyanipennis contained an average of 320, 340, and 390 eggs each, respectively. Cross-mating between nuttalli and viridana and nuttalli–viridana hybrids were observed in the field. Four nuttalli females were seen ovipositing in an area that contained the remains of nesting cells of leafcutter bees (Megachile sp.); these are the first recorded observations of Lytta species ovipositing in the field. The beetles preferred moist, firm soil for oviposition, and the eggs desiccated very quickly when not in contact with moisture. The eggs of these three species developed fairly uniformly at temperatures from 15° to 30 °C, and it appeared to take about 2 to 3 weeks to complete embryological development at temperatures normally encountered during June through August. Relationships among these three species suggested by their behaviour and biology are discussed.

Three known species of scale insects belonging to the genus Matsucoccus occur on pine trees in northeastern North America: M. gallicolis Morr., on pitch pine, Pinus rigida Mill., and scrub pine, Pinus virginiana Mill. (Parr, 1939); M. resinosae Bean and Godwin on red pine, P. resinosa Ait. (Bean and Godwin, 1955); and M. macrocicatrices Richards on eastern white pine, P. strobus L. (Richards, 1960). This last species. in contrast with the others, is closely associated with the fungus Septobasidium pinicola Snell. From 1957 to 1959 personnel of the Forest Insect Laboratory, Sault Ste. Marie, and the Forest Biology Laboratory, Fredericton, collected some 500 specimens from 21 areas in Ontario and the Maritime Provinces. These collections, augmented by herbarium specimens provided by the Forest Pathology Laboratory, Maple, from five other areas in Ontario, not only the insect specimens necessary for the dercription of the species, but information on its biology and distribution.

The effects of the biologically derived insecticide spinosad on parasitoids of Mamestra configurata Walker were studied. Adult Trichogramma inyoense Pinto and Oatman (Hymenoptera: Trichogrammatidae), an egg parasitoid, were as susceptible to a dose of 0.125 μg/cm2 as they were to a high dose of 2.0 μg/cm2. Application of spinosad to host eggs at the time of oviposition resulted in significantly reduced T. inyoense parasitism and higher parasitoid mortality in parasitized eggs. Adult Microplitis mediator (Haliday) (Hymenoptera: Braconidae), a larval endoparasitoid, were highly susceptible at the highest dose tested, 1.0 μg/cm2. Spinosad at 2.0 μg/cm2 fed to larval M. configurata parasitized with M. mediator 1 and 7 d previous caused similar mortality to that for nonparasitized larvae. At a dose of 0.125 μg/cm2, only larvae parasitized 1 d previously showed mortalities similar to those of nonparasitized larvae, whereas larvae parasitized 7 d previously were not affected by this low dose. Larval M. mediator that egressed from hosts parasitized 7 d previously and treated with the low dose were unable to complete cocoon formation and died. This study suggests that integrated pest management programs for M. configurata in canola should include evaluating the presence and abundance of parasitoids.

Populations of leaf rollers on apple can be influenced by the proximity of alternative host plants, notably rose, privet, and antelope bush, in part because larval dispersal is common. Indications are that leaf roller population increases caused by parasite decreases are ultimate consequences of pesticide treatments, so that reductions in spray programs will not necessarily cause potential leaf roller pests to become actual pests. The composition of the leaf roller fauna on apple m the Okanagan Valley becomes increasingly complex as the environmental water balance is changed by cultivation and irrigation. There are indications that heavy vehicular traffic can be harmful to leaf rollers and their parasites nearby.

As part of a detailed study of the life system of the alfalfa weevil, Hypera postica (Gyll.), in southern Ontario, two methods were developed for estimating numbers of eggs in the spring growth of alfalfa. The first is based on direct counts of the eggs, which are laid in clusters and hence, aggregated in distribution; for moderate levels of infestation (ca. 8 eggs per bouquet), estimates with acceptable precision may be obtained by taking a single 3-stem bouquet of alfalfa from 80 randomly selected ft2 (.09 m2) quadrats within a field. The second is based on counts of the oviposition punctures which are randomly dispersed and consistent with the Poisson distribution. Although slightly less accurate, this method will provide a valid index of the number of eggs with less labour; acceptable precision may be obtained by taking a single bouquet from just 32 quadrats.

Intensive and systematic laboratory studies conducted under various experimental conditions (larval stage, physiological condition of the insect, temperature, formulation) revealed that non-crystalliferous strains of Bacillus thuringiensis Berliner and B. cereus Frankland and Frankland were equally pathogenic for larvae of Choristoneura fumiferana Clemens as the crystalliferous strain of B. thuringiensis tested. Also the addition of minute quantities of chitinase (10,000 UN/ha) considerably increased the efficiency of commercial preparation of B. thuringiensis against C. fumiferana.

At 20°C, B. thuringiensis var. kurstaki provoked a slow septicemia in 3rd instar larvae of C. fumiferana which resulted in 90% larval mortality in 27 days. Under the same experimental conditions, a non-crystalliferous strain of B. thuringiensis (No. 17) and two strains of B. cereus, entomopathogens isolated from C. fumiferana and from a Tachinidae, also caused a slow septicemia resulting in 90% mortality of 3rd instar larvae after 30 to 32 days.

Experiments revealed that the symptoms of infection (lethargy, loss of weight) caused by B. thuringiensis + chitinase were far more rapid and pronounced than those provoked by B. thuringiensis alone The commercial preparation 26B prepared by Sandoz-Wander, applied at a rate of 16.8 × 109 BIU/ha caused only 80% mortality of 3rd and 4th stage larvae, while the complex Sandoz + chitinase N.B.C. provoked 100% larval mortality between 9 and 27 days depending upon the experimental conditions used Similar results were obtained with Dipel 36B. For instance, at 20°C Dipel + chitinase N.B.C. provoked 100% mortality of 3rd stage larvae in 9 days, while with Dipel alone, the same level of mortality was reached after 24 days. Also, it was established that C. fumiferana larvae reared on Abies balsamea were far more susceptible to the action of the bacillus than those reared on artificial diet.

These results confirmed that addition of chitinase considerably increased the pathogenic properties of B. thuringiensis on C. fumiferana and the low efficiency of the bacillus alone. The addition of chitinase to commercial B. thuringiensis preparations is required and of prime importance in future use of B. thuringiensis for the control of this insect pest.

A study of sampling variation in field populations of the cabbage maggot, Hylemya brassicae (Bouché), on cabbage in Ontario, revealed that inter-plant and block differences were rarely significant. For the immature stages, the most appropriate sample unit was the plant root together with a 4- to 6-in. diameter core of soil. The number of samples required was inversely proportional to population density; this relationship was graphed for three levels of sampling precision.The insect is bivoltine in eastern Ontario but has three generations in the southwestern part of the province.

A laboratory experiment demonstrated that in San Jose scale, Quadraspidiotus perniciosus (Comstock), the male is susceptible to a number of insecticides. Diazinon was the most effective as it killed the males before they emerged from their shells. Males emerged and survived for a short time before being killed by residues of azinphosmethyl and endosulfan. In an orchard, a petal fall spray of diazinon or Penncap E applied when male scales started to emerge gave good control of San Jose scale and was as effective as three summer sprays of diazinon timed to emergence of crawlers. Penncap E was ineffective against the crawlers. Post-bloom sprays are necessary to control infestations of incrusted scale because a pre-bloom oil application usually fails to contact live scale that may be underneath one or more layers of old dead scale.

Trap crops are a plausible control strategy for the wheat stem sawfly (WSS), Cephus cinctus Norton (Hymenoptera: Cephidae), especially in alternate wheat−fallow cropping systems. Identifying the most suitable winter wheat (Triticum aestivum L., Poaceae) cultivars is necessary to further improve the effectiveness of winter wheat trap crops. We compared cultivars suitable for cultivation in Montana to identify those that exhibit the greatest potential as trap crops. To accomplish this we used nine winter wheat cultivars to analyze plant characteristics that influence the oviposition behavior of the WSS: stem height, stem diameter, rate of plant development, and emission of the WSS attractant (Z)-3-hexenyl acetate. Data on sawfly-induced stem cutting collected from these cultivars in field nurseries were analyzed to evaluate the potential of each cultivar to attract sawflies. Based on these criteria, five cultivars with good potential as trap crops are ‘Norstar’, ‘Neeley’, ‘Morgan’, ‘Rampart’, and ‘BigSky’. More data from laboratory preference tests and detailed measurement of semiochemical production from these cultivars are required for selecting optimal cultivars for trap-cropping.

During May, 1957 near Lumby, B.C., there was a reoccurrence of the gregarious flight behaviour of Priacma serrata males observed the preceding year (Atkins, 1957). Once more these beetles exhibited a strong attraction to “Perfex” laundry bleach, which is an aqueous solution containing 5-5.5 per cent sodium hypochlorite and 4.3 per cent sodium chlorate. They swarmed around the bleach-treated articles every fair day from the 5th of May until the first week of June. This situation presented an ideal opportunity to study certain aspects of the behaviour of this strange insect and accordingly observations were made on the beetles' flight both in the field and under laboratory conditions.

Because black flies are active for only a few months each year in the vicinity of this laboratory, methods for collecting, extracting, sterilizing, and storing eggs were devised to facilitate a year around program of research. These methods were developed partly from existing entomological and limnological techniques.

By restricting the swarming behaviour of Chironomus riparius Meigen, in a series of five swarm suppression cages, it was found that reduced swarming resulted in fewer matings and less oviposition. With total suppression of swarming no matings occurred.

When swarming volume was incrementally reduced vertically or horizontally, it was found that the minimum vertical or horizontal dimension for swarming to occur was 2–3 cm. The mating rate was determined by the detection of labelled spermatozoa in autoradiographs. Thus swarming appears to have an epigamic function in C. riparius and is an essential precursor to mating and oviposition.

The species of the genus Isonychia Eaton, 1871 (Isonychiidae) of East Palaearctic are revised. Two subgenera, Isonychia s.s. and Prionoides Kondratieff et Voshell, 1983, are represented in the Palaearctic. New species and subspecies of Isonychia s.s. are described: I. sexpetalasp. nov., I. ussurica sibiricasubsp. nov., I. concoloriasp. nov., I. crassiusculasp. nov., and I. vshivkovaesp. nov. with subspecies I. vshivkovae vshivkovae and I. vshivkovae sinitshenkovaesubsp. nov. A new species group japonica, with three species (I. crassiuscula, I. vshivkovae, and I. japonica), is recognized on the basis of adult and larval characteristics. The name Isonychia hainanensis She et You, 1988 is synonymized with Isonychia ignota (Walker, 1853) syn. nov.

After diapause was initiated in reproductively active adults, short-day (LD 12:12) maintained diapause and prevented oviposition for 66 ± 22 days. Subsequently all females remaining in the conditions that produced diapause (LD 12:12), began to lose the red-brown diapause coloration and began to oviposit. When animals were transferred to long-day at various intervals during diapause, oviposition resumed within similar time periods, thereby indicating that the intensity of diapause did not differ at the times tested.We suggest that in nature the short days of early autumn induce diapause, that the short days of late autumn maintain this diapause, that subsequently diapause ends under short-day conditions and that factors other than photoperiod, such as temperature accumulations, play a primary role in timing the initiation of reproduction in late spring.

It has been observed (4) that when the first attacks of Dendroctonus monticolae Hopkins and D. brevicomis LeConte were successfully established on ponderosa pines, the trees were subsequently invaded by a large number of beetles. This abrupt rise in the attack intensity has been termed the “mass attack”. In the absence of successful initial or “pioneer” attacks the mass invasion did not occur. The successful establishment of initial attacks and the occurrence of the subsequent mass attack were found to be correlated with low oleoresin exudation pressure (o.e.p.) of the trees observed.

Like all other Tryphoninae, the European species of Exenterus have eggs that are attached to the host by a stalk inserted into the host integument. Their eggs present an interesting series of evolutionary steps from the typical tryphonine condition in which the egg has a small single stalk with a knob-like anchor to an extremely specialized condition in which the stalk is doubled and its two parts migrate to opposite ends of the egg; the anchoring part of the stalk is concurrently enlarged until it half encloses the egg and functions as an extremely efficient organ of attachment to the host cuticle. In dry periods the simple type of stalk becomes brittle and easily broken, resulting in the death of the parasite. The specialized eggs with protected stalks are not subject to such hazards; thus species with specialized eggs can succeed in drier climates and can better survive droughty seasons. Correlated with these specializations is an increase in range of species, and greater abundance of individuals. The success of the European species introduced into North America for biological control has been roughly proportional to the amount of specialization in the egg structure. Little is known of the life histories of the American species of Exenterus but the few facts available do not appear to contradict the type of correlation exhibited by the European species.

We evaluated host discrimination and oviposition restraint in the wasp Praon pequodorum Viereck, a solitary parasitoid of the pea aphid, Acyrthosiphon pisum (Harris). In dichotomous preference tests, wasps attacked more unparasitized than equally available parasitized aphids, and more self-parasitized aphids than aphids parasitized by conspecific females. The conditional probability of a female laying an egg into an attacked aphid was independent of the host type. Host discrimination apparently involves a volatile and individual-specific pheromone marker. Females expecting to compete with other (conspecific) wasps for a limited host supply may ensure possession of the host by self superparasitism. Because host examination requires considerably more time than oviposition in P. pequodorum (and eggs contain few resources), it may be adaptive for a female to lay an egg in an examined host regardless of variations in host quality.