Studies were carried out to investigate the growth response of normal and defoliated spring wheat. Plant growth is expressed by the von Bertalanffy (1957) growth equation modified to allow for declining growth potential with age. Grasshopper damage was assessed by comparison with artificial defoliation and results indicated a simple linear relationship between grasshopper food consumption and defoliation damage. On the basis of this relationship it indicated that grasshoppers feeding on wheat waste 6.2 times as much foliage as they actually consume. Damage to foliage is translated into an effect on grain yield by an allometric relationship between total plant weight and yield. A simulation model indicating the time course of plant biomass provides realistic estimates except in the case of acute defoliation.

A new genus and species, Playaspalangia rothi, is described from Sonora, Mexico, in the intertidal zone of algae-covered rocks.

Within-tree larval and progeny adult populations of Dendroctonus frontalis Zimm. attacking loblolly pine, Pinus taeda L., were investigated in order to define the distribution of larvae within sample units (100 cm2 disks of bark) and to describe the functional relationship of both larvae and progeny adults to the infested portion of the tree bole.

Larvae and progeny adults were sampled over the infested bole of the 50 trees. Two separate measures of progeny adults were obtained. The first measure was taken just prior to emergence from the tree and the second measure was obtained by rearing the insect until emergence from the sample disks was completed.

Larvae were found to be uniformly distributed within the total disk. The functional relationship of the larvae and the two measures of progeny adults to the normalized height on the infested bole was described by the two parameter nonlinear model y = Ax(1−x)eBx.

Highest larval density along the infested portion of the tree bole occurred just below the center and tapered abruptly towards the base and gradually towards the top of the tree. The density of progeny adults on the other hand was greatest just above the center portion of the infested bole and tapered abruptly towards the top and gradually towards the base of the tree. Both measures of progeny adults produced curves of virtually the same shape. However, the density of progeny adults was substantially less in the samples which were reared indicating that mortality agents continued to act on the population until emergence from the tree.

Laboratory studies on the biology of the carrot weevil, Listronotus oregonensis (LeConte), were performed at 21° and 27 °C. At 21 °C females laid eggs for 88 days on carrot slices and 94 days on foliage. Egg production per female averaged 156 and 175 on slices and leaves respectively. Eggs hatched after 8.3 days incubation and the larval stage comprising four instars was completed in 19.1 days. The prepupal and pupal stages lasted 3.7 and 9.4 days respectively. The complete life cycle including an average preoviposition period of 17 days was 57.6 days. Development was more rapid at 27 °C, with the complete life cycle taking only 37 days.

Data obtained by sampling studies during 1972 and 1973 were used to develop equations for predicting the number of adult pecan weevils, Curculio caryae (Horn), in a tree from the number of pecan weevils trapped beneath that tree on a given date. Two of the models then were tested to determine their effectiveness in estimating weevil populations.

When the population estimates obtained from the model built from the early season data in 1972 (model A) were compared with the actual populations found in the trees in 1973, it was found that 71.7% of the observed values in 1973 fell within the 95% confidence intervals for the predicted values. When similar comparisons were made utilizing the model built from early season data in 1973 (model C), 95% of the observed population values in 1972 fell within the confidence intervals for the predicted values. Three-dimensional response surfaces generated from the models were similar and revealed that as the season progressed, the number of pecan weevils predicted from any trap value increased at an increasing rate.

Sticky traps caught large numbers of mites that adhere tightly or ride in protected places on attacking southern pine beetles and retrieved some of the mites that are loosely attached. Of the 2539 beetles surveyed, only 39.6% carried mites. Seven species of phoretic mites were found; the two most common, Tarsonemus krantzi and Trichouropoda australis, showed no preference for either beetle sex but preferred to ride on specific parts of the body.

A technique is described for rearing successive generations of the insect in numbers from 200 to 40,000 continuously without diapause. All components of the diet are commercially available and the principal ingredients are of plant origin. Survival at four stages of development is given and the causes of mortality are discussed. The per cent survival of insects from instar III to pupation times the percentage of perfect female pupae obtained at harvest gives a factor considered to be the best measure of the worth of an artificial diet. The variability of these statistics is shown by frequency distributions obtained in 50 independent tests of the diet. Overall survival of 84% times 73% perfect females gave a diet worth factor of 61. An analysis of rearing costs is presented. Although 15 continuous generations have been reared, egg production of the highly selected strain has not deteriorated.

Conotrachelus neomexicanus Fall occurs throughout the range of Pinus ponderosa Laws. in the central and southwestern United States. It is commonly found infesting ponderosa pine cones in north-central Colorado. C. neomexicanus is univoltine. Eggs are laid in second-year cones from May through July. Larvae mine extensively in the cones and drop to the ground for pupation in the soil. Adults emerge from the soil in late summer and early fall, return to the trees to feed on twigs, and presumably hibernate in sheltered locations during the winter A tachinid fly, Myiophasia sp. nr. ruficornis Tns., is an internal parasitoid of weevil larvae.

Efficient methods are described for mass rearing, picking and spreading in the field millions of aphids. The originality of the method lies in the use of a powder that prevents aphids from sticking to the equipment or to each other, and makes them a flowable substance that can be spread with a special apparatus.

The genus Anatis is reviewed and six species are recognized: ocellata (L.), mali (Say), labiculata (Say), halonis Lewis, rathvoni (Lee.), and lecontei Casey. Relevant illustrations and a key to the species are given. Neotypes for mali and labiculata have been selected.

The effects of temperature on rates of oviposition and development of immature stages of Pissodes strobi from Sitka and white spruce were investigated in the laboratory. Maximum rate of oviposition occurred at 20° to 26 °C. Brood development from egg to emergence took 888 and 785 degree-days above a threshold of 7.2 °C for the weevil from Sitka and white spruce, respectively.

Life-table study plots were established in southeastern Manitoba to study the population dynamics of the larch sawfly for the 1956 to 1972 generations and to evaluate the impact of two recently introduced parasites.

Abbreviated life tables were used to calculate k-values, expressions of mortality during the different stages due to various factors. Graphical and principal component analyses of the k-values showed that mortality during the cocoon and adult stages (k5) largely determined population trends. None of the factors affecting populations before the introduction of the parasite Olesicampe benefactor Hinz was density-dependent. However, a form of density dependence appeared to exist for O. benefactor and for its hyperparasite Mesochorus dimidiatus Holmgren. The area of discovery for both species decreased rapidly as the density of the female parasites increased.

A simple model confirmed that k5 was largely responsible for determining population trends. A second model utilizing the relationships between areas of discovery and adult female densities for O. benefactor and M. dimidiatus provided reasonable approximations to observed values for numbers of sawfly eggs, and numbers of adults, rates of attack, and attacks per female for both species of parasites.

Twenty sets of 50 pairs of randomly generated values of k5 were used as simulated input in the second model. None of the values for simulated egg populations of the larch sawfly reached outbreak proportions when O. benefactor and M. dimidiatus were present, but most exceeded these levels in their absence. Larch sawfly populations in southeastern Manitoba should be controlled by O. benefactor in the foreseeable future.

Differential survival and development rates were obtained for the bertha armyworm, Mamestra configurata Wlk., reared at nine constant temperatures. Eggs and larvae had high survival rates at temperatures ranging from 8 °C to 32 °C and pupae showed good survival between 8 °C and 28 °C. Eggs and larvae did not complete development at 6° and 36 °C; and 32 °C was lethal for pupae. Duration of the egg, larval, and pupal stages decreased as the temperature increased from 8 °C to 28 °C. When duration and developmental rates were plotted against temperatures, the observed points did not differ significantly from curves formulated from the logistic equation 1/y = K/(1 + ea−bx). With a developmental threshold of 7 °C, 82, 356, and 352 accumulated day-degrees above the threshold were required for development of eggs, larvae, and pupae, respectively.

Three western species of tussock moths of the genus Orgyia are all susceptible to infection by the same two nuclear polyhedrosis viruses. An eastern species of Orgyia is also affected by these viruses. In the Western States, the natural occurrence of the two viruses appears to be limited to definite geographic areas. Infectivity of the viruses for hosts outside the genus Orgyia is not known. One report of such cross-infectivity could not be substantiated. Bodies which appear to be composed of viral materials but which are not normal virus particles are sometimes found occluded in polyhedra.

Continuous trapping on the bark surface of trees infested with Dendroctonus brevicomis LeConte was carried out during six beetle generations from June 1969 to November 1971, at the University of California’s Blodgett Forest Research Station in the central Sierra Nevada mountains. Significant linear correlation was found between the density of D. brevicomis trapped on the surface of infested trees and the initial within-tree beetle densities. In the first beetle generation, mass arrival was rapid and intense (averaging 1167 beetles per 2.7 sq. dm of trapping surface on each tree, during a mean of 8.8 days). The arrival patterns during this generation were quite consistent between trees. During the second generation, mass arrival was prolonged over a mean of 19.4 days and fewer beetles were trapped ( per 2.7 dm2 of trapping area per tree). The patterns of arrival were more variable during this second generation. In generation 1, with the exception of one tree, the beetles were distributed equally at the three trapping heights (4.5, 7.5, and 10.5 m). In generation 2 they were more abundant on the traps at the lower portions of the tree.

Fluorescent powders provided an effective method for marking and monitoring flight activities of adults of Glischrochilus quadrisignatus (Say), a pest of processing tomatoes. Observations and experiments were conducted that would have been impossible with unmarked insects.

Experiments showed that small numbers of beetles located hampers with damaged tomatoes placed 300 m from a release point within less than 2 h. Tomatoes picked and cracked 1, 2, or 3 days prior to release of marked beetles attracted beetles in a ratio of 1:2:3. Approximately 3.5 times as many starved as fed beetles were attracted to damaged tomatoes. Most of the beetles landed on the ground near the hampers and entered via the floor, rather than landing on tomatoes at the top of the hamper.

The significance of the above four findings in relation to control of the insect is (1) beetles are probably attracted to damaged tomatoes from a wide area; (2) tomatoes should be harvested as close as possible to the scheduled time of delivery to the factory; (3) more severe infestations could occur subsequent to periods of inclement weather when beetles, are unable to move to new food sources; and (4) the treatment of hamper floors with insecticides before harvest may assist in control.

The larvae of Simulium arcticum Malloch in three collections from the North Saskatchewan River of May and June 1969, 1971, and 1974 showed seven instars. The first instar larva possessed an egg burster and the seventh instar larva possessed separated cervical sclerites. The intervening instars, however, could be decisively identified only by measuring the lengths of the postgenae. The observed mean postgenal lengths for all but the seventh instar were near those predicted by the regression line logeY = 4.1216 +.2927X. The observed mean lengths of whole larvae of all seven instars were near those predicted by the regression line logeY = −.5234 +.3238X but with relatively large standard deviations. Thus there were geometric increases in size between successive instars.

The systematic status of the genus Tarsocheylus Berlese, 1904 and the position of the family Tarsocheylidae Atyeo and Baker, 1964 in the Prostigmata is reviewed. The family does not belong in either the Raphignathoidea or the Anystoidea but in its own superfamily, the Tarsocheyloidea, which is described for this purpose. In turn, this superfamily is placed alongside the Heterocheyloidea in the Heterostigmata.

Because the type-species of Tarsocheylus, T. paradoxus Berlese, 1904, is conspecific with Hoplocheylus discalis Atyeo and Baker, 1964 (new synonymy), the concept of Hoplocheylus Atyeo and Baker, 1964, which has remained until now as originally proposed, is the same as that of Tarsocheylus. However, a new case is made for recognizing these genera as mutually distinct, based on other morphological criteria. Tarsocheylus atomarius Berlese, 1913, the type-species of Hoplocheylus, is apparently conspecific with Hoplocheylus canadensis Marshall, 1966 (new synonymy) and perhaps with one or two other described species from North America. A third generic entity, represented by Hoplocheylus johnstoni Atyeo and Baker, 1964, is noted but not named or formally described. Hoplocheylus pickardi Smiley and Moser, 1968 is conspecific with H. similis Delfinado and Baker, 1974 (new synonymy).

Hemitarsocheylus Soliman and Zaher, 1975, which was described as a new genus in the Tarsocheylidae, is congeneric with Stigmocheylus Berlese, 1910 (new synonymy). This genus does not belong in the Tarsocheyloidea, but rather in the Anystoidea.

A list of character states found useful in recognizing groupings of species of Tarsocheylidae is presented. Based on the collection data with specimens representing described and undescribed species at hand, the known distribution of the Tarsocheylidae is extended to include Australia and western North America, and the second known instance of an association with passalid beetles is recorded.

From a phylogenetic standpoint, the Tarsocheyloidea and Heterocheyloidea are proposed as sister groups that together constitute a new suprafamilial taxon, the Tarsocheylina. In turn, the Tarsocheylina and Tarsonemina are proposed as sister groups, and both are described; together, they form the Heterostigmata.

The systematic and phylogenetic relationships of the Heterostigmata (including the Tarsonemina) to the Prostigmata and the Astigmata are reviewed. Not only should the Heterostigmata be retained in the Prostigmata but it should be lowered in hierarchic rank, such that it is a part of the Eleutherengona. The stock that gave rise to the Anystoidea and related superfamilies is shown to be ancestral to the Heterostigmata as well.

Development of P. pallipes, from egg to emerged larva, in the tarnished plant bug lasts 24.49 ± 2.38 days at 25 °C/16 h and 20 °C/8 h and 77 ± 5% R.H. with 16 h illumination.

Eggs of P. pseudopallipes need 72–96 h to hatch under the above-cited regime. At least three distinct larval stages can be recognized without special staining procedures. The first instar larva is a caudate-mandibulate type. The second larval stage is acaudate and lives in the host haemocoele. The third larval stage is also acaudate and emerges from the host. The pupa is an exarate type diapausing in a cocoon. P. pseudopallipes is an arrhenotokous species. The longevity of the adults in the laboratory is about 16 days. The adult oviposits into the host abdomen.

Survival of diapausing pupae is better at 16 h photophase than at 8 h photophase.

A key is given to the species of Aphis L. on Ribes spp. in North America, including, A. bulleri new species and A. manitobensis new species. A. ribigillettei Knowlton and Allen and A. sanborni Patch are declared to be synonyms of A. neomexicana Cockerell, and A. tonahasa Hottes is considered to be a nomen dubium.