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A family of high-frequency models for operational amplifier difference-mode gain are derived from measured frequency-response data, using a complex curve-fitting technique by Levy. This technique finds a model of a desired order which minimizes a weighted sum of squared magnitude and phase errors at discrete frequencies. First- to fourth-order models are derived, with the fourth-order model being accurate over a considerably wider frequency range than a previously published model.

Field studies in western Massachusetts in 1972–73 showed that Crioceris asparagi (L.) (Coleoptera: Chrysomelidae) has 2 full generations and a partial 3rd generation annually. The primary natural control agent was Tetrastichus asparagi Crawford (Hymenoptera: Eulophidae) which fed upon 50% of the host eggs and parasitized nearly half of the remaining eggs. Several carabids, a nabid, and a pentatomid were found to prey upon C. asparagi larvae. Coccinellids were an important mortality factor, preying on both eggs and larvae of the asparagus beetle; aphids appear to function as attractants for ladybird beetles. No pathogens of C. asparagi were discovered. Data on age-specific mortality are presented.

In past years, control of the cherry case bearer, Coleophora pruniella Clem. by dormant oil emulsion sprays has been quite successful on cherries but often failed almost entirely on apples. High percentages of kill on apples were made in 1932. The keynote to successful case bearer control is shown to be thorough spraying from the ground. However, applications thorough enough to give a satisfactory kill often give excessive tree injuries in the Door Peninsular fruit growing area. Dormant lime sulfur was tried in an effort to control this insect without tree injuries, and preliminary trials with it are most encouraging.

The nutrition of the German cockroach, Blattella germanica (L.), was first studied by Zabinski (1928, 1929) who observed that these insects required “vitamin B” but that they could grow fairly well on diets inadequate for vertebrates. Somewhat later McCay (1933) suggested that this species be used as an assay animal for certain “vitamin B” fractions. Semi-synthetic diets were employed by Melampy and Maynard (1937) in a general survey of the requirements of this species. Recently a method of rearing the German cockroach has been developed which enables it to be used for quantitative studies of dietary requirements (Noland et al , 1949). By use of this procedure, it has become possible to determine specific requirements of the cockroach for various dietary components. The present paper describes a synthetic diet on which the growth rate of B. germanica equals or exceeds that on the best crude diet known. By suitable variations of this diet the effects of 11 single vitamin deficiencies on the growth of B. germanica have been determined. Preliminary comparisons have also been made of the growth responses of Periplaneta americana (L.) and Blatta orientalis (L.) when fed a synthetic diet and a crude diet.

Although rapid advances have been made in the study of insect nutrition during the past decade, the nutritional requirements of the great variety of insects which feed on living plant material has received little attention. The paucity of reports on attempts to rear phytophagous insects on either purified or synthetic diets may be due in part to the difficulties encountered in (1) maintaining reasonably aseptic culture conditions and (2) devising a medium which possesses a texture acceptable to an organism normally feeding on living plant parts.

Cockroaches are popular insects for experimental studies, for they are readily available, of a convenient size, and grow at all seasons of the year. Their method of reproduction is such that a large number of nymphs hatch at once, making them ideal experimental animals for comparative quantitative studies. It is surprising, therefore, that no standard methods of rearing these insects have come into general use. A review of the more common methods of laboratory culture was presented by Campbell and Moulton (1943).

Orientation reactions of the wire worm, Melanotus communis Gyll., to various insecticide seed treatments were studied by following the movements of individual larvae tagged with radio-active cobalt in the soil. It was found that the repellency of certain insecticide seed treatments to wireworms apparently has two components: (1) inhibition of the feeding reaction, and (2) orientation of the insects away from treated seeds. For convenience these are referred to as type one and type two repellency, respectively. Type two repellency does not preclude contact with treated seeds, and varies in degree depending on the insecticide used. Aldrin, dieldrin, endrin, heptachlor and lindane seed treatments all appeared to posses considerable type one repellency Type two repellency was most pronounced with lindane-treated seeds, and with aldrin-treated seeds where this insecticide was not used in excess of 1 ounce of actual toxicant per bushel of seed. Dieldrin, endrin and heptachlor seed treatments showed a degree of type two repellency intermediate between lindane and aldrin on the one band and untreated control seed on the other.

The thirty-second annual meeting of the Eastern Branch, Entomological Society of America, was held at the Hotel New Yorker. A total of 258 entomologists and student entomologists registered at this meeting. E. N. Woodbury, Chairman, presided. The opening general session on October 27 began with the introductory remarks of the chairman. Following this, the president of the Entomological Society of America, M. P. Jones. delivered an address. Next. the report of the Execxutive Secretary of the Entomological Society of America, R. H. Nelson, was given. Neely Turner, Eastern Branch Representative to the Governing Board of the Entomological Society of America presented his report following Mr. Nelson.

A method was developed for testing insecticides against newly hatched larvae of the little house fly, Fannia canicularis (L.), which were exposed continuously to a toxicant mixed in poultry droppings as a culture medium. In screening tests, 13 insecticides were mixed with poultry droppings prior to insertion of the larvae. These materials were: Bacillus thuringiensis , fenthion, coumaphos, dimethoate, Ciodrin® (α-methylbenzyl 3-hydroxycrotonate dimethyl phosphate), diazinon, dicapthon, dimetilan, ronnel, malathion, trichlorfon, carbaryl, and Zytron® (0-2,4-dichIorophenyl O-methyl isopropylphosphoramidothioate). Of these, B. thuringiensis, dicapthon, malathion, and carbaryl were eliminated in the preliminary tests. The remaining materials were compared for initial effectiveness and for persistence in poultry droppings after 48 hr. The toxicants differed in their stabilities in droppings as well as in their initial toxicities. Dimethoate was substantially more effective than any of the other materials tested and it maintained its toxicity well up to 48 hr in the manure. Next to dimethoate, coumaphos and diazinon were about equal in effectiveness as larvicides. In initial effectiveness, the concentrations of toxicants (milligrams of active ingredient per kilogram of droppings) that produced 90% or greater mortalities were: 0.5 dimethoate; 1.0 diazinon and coumaphos; 2.0 trichlorfon, ronnel, fenthion, and dimetilan; 4.0 Zytron and Ciodrin. Forty-eight hours after the toxicants had been mixed with poultry droppings, greater than 90% mortalities to newly hatched larvae added to the droppings were produced by the following levels: 1.0 dimethoate; 2.0 diazinon and coumaphos; 4.0 Zytron, ronnel, fenthion, and dimetilan. Ciodrin and trichlorfon showed poor persistence.

Wireworm control is necessary for the successful production of some crops in almost every important agricultural region of the world. The techniques used to follow wireworms in the soil, however, have always left much to be desired. Until recently the methods used were very artificial and the wireworm habitat had to be interrupted so that the insect could be studied. This problem has been solved by recent developments in the use of radioactive isotopes. By using radioactive nuclides whole animals such as insects can be traced. The insect is allowed to move about in any direction, and the natural environment is no longer altered as in other procedures.

An investigation of the digestive epithelium of the European corn borer during the winter diapause was carried out in conjunction with nutrition and food habit studies of the larvae of this insect. Histological changes associated with metamorphosis were observed at the onset of diapause, and the study became one of tracing the prepupal changes in the epithelium of the mid-gut. The European corn borer passes the winter as a mature larva in diapause. The larva pupates in the spring without further feeding. The use of the overwintering generation of larvae for studies of prepupal changes has an advantage in that the rate of the developmental changes that occur is greatly retarded by the low environmental temperatures. The several phases of metamorphosis are therefore more distinctly separate than is the case with the generation which matures and pupates during the summer. The observations reported here were repeated in studies of the histological changes associated with metamorphosis in larvae which pupated during the summer, and the same developmental changes were found to occur.

A formulation of 40% Thimet was mixed with 4-16-8 fertilizer and used to treat the soil or 8 by 8 foot plots at rates of 0, 1, 2 and 4 pounds of Thimet per acre where small grains were subsequently grown. The objectives were: (1) to see if these treatments would reduce the incidence of “blue dwarf” disease of oats by killing a possible arthropod vector, and (2) to study the Thimet residue toxins, if any, present in oat, wheat and barley plants at different intervals after planting. The disease readings were made by visual inspection after the oats had headed; the chemical analyses were made by the method of Hensel et at . (1954) as modified by Curry (1956). The following results were obtained: (1) Thimet residue toxins were found as early as 26 days and as late as 47 days after planting but none was recorded in 36 analyses made on plants or grain 68 days or more after planting; (2) the incidence of blue dwarf disease on oats was not substantially reduced by the Thimet treatments under the conditions of this experiment; (3) the Thimet-fertilizer mixtures did not cause any apparent phytotoxicity to the three crops tested.

Guthion® ( O, O -dimetht S -(4-oxo-1,2.3-benzotriazin-3-(4H)-ylmethyl) phosphorodithioate) was incorporated into chick starter feed at levels ranging from 9.5 p.p.m. to 2,177 p.p.w. and fed to day-old chicks, Within a week depression in gains in weight was observed at the 306-p.p.m. level, and depressions in gains in weight became progressively more severe as the concentration of Guthion was increased. At the 2,177-p.p.m. level 95% mortality occurred during the second week. Tests with starter feeds containing Guthion at levels of 100 and 600 p.p.m., alone and in combination with two different coccidiostats (Nicarbazin and Sulfaquinoxiline), did not reveal any adverse interactions. Chemical analyses of Guthion-feed mixtures, stored in metal containers with tight fitting lids, showed that Guthion disappeared fairly rapidly.

The appearance and prevalence of the face fly, Musca autumnalis DeGeer, is suspected as a contributing factor in the increase of infectious bovine keratitis (pinkeye) in cattle. Preliminary studies were initiated in Massachusetts to determine the potential role of the face fly in the transmission of this disease. The more significant findings are: (a) the bacterium Moraxella bovis (Hauduroy) may remain viable in the environs of the fly up to 3 days; (b) M. bovis was readily recovered from the exudate from infected eyes; (c) M. bovis was readily recovered from wings and legs of face flies up to 3 days after exposure to laboratory cultures; (d) the bacterium apparently is rapidly destroyed in the digestive tract of the face fly; and (e) M. bovis was recovered from laboratory-reared flics exposed to lacrimal exudates on infected cattle in the field. Since the fly is a persistent feeder around eyes of cattle, these findings are further evidence tending to incriminate the face fly as a potential carrier of M. bovis .

Encapsulated Rabon® (2-chloro-l-(2,4,5 trichlorophenyl) vinyl dimethyl phosphate) was fed to Salmon sex-link hens continuously in massive dosages (800 ppm) mixed with mash for a treatment period of 90 days. The effects on body and organ weights as well as on egg production, and feed and water consumption were recorded. The general appearance and behavior of the birds were also observed. Blood counts and a general gross autopsy were carried out on both control and treated birds after slaughter. The shell thickness and interior quality of the eggs were also evaluated. No inhibition of physiological activity or decrease in reproductive performance was noted. Analysis of body tissues and egg yolks yielded minute quantities of residues in some samples.

Wire worms, Melanotus spp., were held in quart-size fruit jars containing moist soil and treated seeds to study the relative efficiencies of various insecticide seed treatments in killing them and protecting the sceds from their feeding. The abilities of the insecticide treatments investigated to kill wire worms were ranked as follows: aldrin, good; heptachlor, fair; lindane and dieldrin, mediocre; endrin, poor. Aldrin and lindane were the most repellent of these insecticides. The relatively greater repellency of aldrin, as compared with heptachlor or dieldrin, was attributed primarily to type two repellency. However the relatively high toxicity of aldrin made it first choice among the insecticides investigated, in spite of this repellency. The relatively greater repellency of lindane, as compared with heptachlor or dieldrin, was attributed to a combination of two kinds of repellency (types one and two). This repellency appears to cause lindane to rank no higher than third among the insecticides investigated from the standpoint of potential usefulne5s as a corn seed treatment for controlling wire worms. Heptachlor and dieldrin showed less type one repellency than lindane, and less type two repellency than aldrin or lindane. It was suggested that the inherent toxicity of heptachlor make it a better wire worm killer than dieldrin, and that this toxicity combined with lower degree of both type one and type two repellency make it a better wire worm killer than lindane.

During a study of natural control agents affecting the European corn borer, Ostrinia nubilalis (Hbn.), in Massachusetts, we determined the presence of Nosema pyraustae Paillot in the borer populations. The latter is a microsporidian parasite of the corn borer which reduces larval growth and survival rates and adult life span (Kramer 1959b, Zimmack et al. 1954). Infected females lay fewer egg masses containing fewer eggs, about half of the latter being infected transovarially (Kramer 1959b, Zimmack and Brindley 1957). Kramer (1959a) reported that this disease interacts with temperature extremes to cause mortality in host populations in the field. The morphology and life cycle of N. pyraustae have been studied (Hall 1952, Kramer 1959c). Raun et al. (1960) described a quantitative method to determine incidence and intensity of infection and gave such data from corn borer samples taken from 8 different states. Among the states represented were Pennsylvania and Delaware, the only eastern states from which this disease has been reported.

Some aspects of the relationship of the predator/egg larval parasitoid, Tetrastichus asparagi Crawford, and its host asparagus beetle, Crioceris asparagi (L.), were examined. Comparative development of parasitoid and host is presented. The parasitized host beetle, although supporting ca. 4.75 developing T. asparagi, exhibits no signs of parasitism until the prepupa has prepared a pupal cell in the soil. T. asparagi feeds on newly deposited beetle eggs and oviposits within eggs containing more advanced embryos.

Several insecticides were tested to evaluate aphid control in Connecticut Valley gladiolus plantings. In 1971, no treatment had significantly fewer alate or a significantly lower total number aphids than the untreated control. In 1972, the number of alate aphids recorded on plants treated with either carbofuran 4 F or oxydemetonmethyl was significantly less than the untreated control. Overall, aldicarb-treated plants had a significantly lower total number of aphids per plant than the untreated control. Irrespective of reductions in aphid numbers, no significant differences were detected in the percentages of plants showing floral symptoms of cucumber mosaic virus disease. Little or no aphid colonization occurred on treated or untreated gladiolus plants. The majority of aphids observed on gladiolus was alates. The following species were collected in the experimental plantings: Aphis fabae Scopoli, A. gossypii Glover, A. craccivora Koch, A. maidiradicis Forbes, Capitophorus hippophaes (Walker), C. elaeagni (DelGuercio), Myzus persicae (Sulzer), Rhopalosiphum Maidis (Fitch), R. fitchii (Sanderson), Myzocallis Punctata (Monell), M. walshii (Monell), M. alnifoliae (Fitch), Macrosiphum venaefuscae (Davis), M. euphorbiae (Thomas), Macrosiphum sp., Nasonovia ribisnigri (Mosley), Therioaphis trifolii (Monell), Acrythosiphum pisum (Harris), Calaphis betulaecolens (Fitch), Monellia sp., Tinocallis ulmifolii (Monell), and Pemphigus populitransversus Riley.

Data were collected to determine effects of certain systemic insecticides on gladiolus growth. No significant differences were detected in plant emergence or height 17 and 23 days, respectively, after planting. At peak bloom, granular soil treatments of aldicarb, oxamyl, and disulfoton showed significant positive effects on gladiolus growth, as indicated by plant heights, flowerhead lengths, and bud numbers. Cucumber mosaic virus-infected plants in aldicarb and disulfoton-treated plots also showed growth benefits. No significant differences in corm weights were detected between treatments.

This was a laboratory investigation in which wire worms ( Melanotus communis Gyll.) were exposed to granulated formulations of soil insecticides in quart-size Mason jars. The insecticides employed were aldrin and heptachlor (in separate experiments), and the carriers were No. 4 Vermiculite and 30-60 meshclay . Insecticide concentration were 2, 5, 10 and 20% on both carriers, plus 30 and 40% on Vermiculite and the insecticide dosages were 1.25, 2.5 and 5 pounds per acre. Final readings were made 21 days after the experiments were started. The following conclusions were reached as the result of this work. (1) Granulated Vermiculite was a very satisfactory carrier for both soil insecticides under the conditions of these experiments; No. 4 Vermiculite compared favorably with 30-60 mesh RVM-AA Attaclay. (2) When Vermiculite was used as the carrier for either aldrin or heptachlor there was some decease in insecticidal efficiency as the concentration of toxic ant increased, but the differences between concentration were not significant in either experiment. (3) With the Attaclay carrier in insecticidal efficiency as the concentration of toxic ant increased, and the number of particles correspondingly decreased, in both experiments.

White leghorn hens were fed mixtures of 50% coumaphos oral drench powder, and pelleted poultry feed. The insecticide levels were 0, 25, 75, and 125 mg of active ingredient per kg of feed. The mean mortalities of larvae of Fannia canicularis (L.) exposed to the droppings from these birds were 7.3, 18.0, 42.5, and 91.0%, respectively. Therefore coumaphos provided an effective degree of control when fed at the 125 mg/kg level. By a comparison of the concentrations of coumaphos required to produce approximately 90% mortality of the fly larvae in this field test with the results of our laboratory tests, it was estimated that approximately a 70-fold decrease in effectiveness occurred during passage of the insecticide through the birds.