Apterous Females Research Articles

Observations on the Life History of the Pinyon Needle Scale Matsucoccus acalyptus (Homoptera, Coccoidea, Margarodidae)

The pinyon needle scale infests pinyon, single-leaf pinyon, and foxtail pines in the southwestern United States. Apterous females emerge in April, are mated by winged males, oviposit, and the resulting scales feed on the needles. Males pupate on the ground in the fall or the following March.

Biological Observations on some Thynnids of Western Patagonia

During a survey for whitegrub parasites, six Thynnid species were found in parts of western Patagonia and studied in varying degrees of detail.Definite host records are established for Elaphroptera scoliaeformis (Hal.), E. (Paralycus) sp. near nigripennis (Smith) and Pseudelaphroptera brevipilosa Durán, which are solitary external parasites of the mature larvae of Aulacopalpus pilicollis (Fairm.) (Rutelinae), Macrosoma glacialis (F.) (Melolonthinae) and Adioristus acuminatus Hust. (Curculionidae), respectively.No adult feeding was observed during the mating flight of E. scoliaeformis and E. sp. near nigripennis, but pairs of P. brevipilosa and Ornepetes semicincta Turner fed extensively on flower heads of Umbelliferae. Some evidence is presented suggesting that at the conclusion of the mating flight the winged males tend to return the apterous females to the sites where they picked them up.Hosts are permanently paralysed and malaxated before eggs are laid on them. The eggs of the two Elaphroptera species are placed parallel to the longitudinal axis of the host, on the mid-ventral line of abdominal segments two to seven. In the case of P. brevipilosa, the egg is lightly cemented by its caudal end at an angle of about 45 degrees to the host surface, the attachment being near the spiracular line of the host and between the third thoracic and sixth abdominal segments.There are five larval instars. The larvae do not normally move over the host surface. In the first four instars feeding is by suction, but the fifth-instar larva tears a hole in the host in the region of the earlier feeding punctures. The film of liquid with which the larva is bathed is produced from its posterior extremity and is not exuded from the feeding puncture. Cocoons of two types may be recognised, corresponding to the sexes, the female type being the shorter and of more rigid construction.E. scoliaeformis, E. sp. near nigripennis, and P. brevipilosa have a single generation a year. The period from egg deposition to cocoon formation is generally covered in three weeks, and at least nine months are spent in the cocoon as a mature larva or prepupa. Adults probably live up to two months.The only natural enemies observed were a Bombyliid of the genus Acrophthalmyda and a Carabid predator, Cnemacanthus sp., attacking the cocoon stages of E. sp. near nigripennis. The adult of this Thynnid is also attacked by a mimicking Asilid fly, Lycomya germainii Big.The function of the mating flight and the economic value of members of the Thynnidae as controlling agents for Scarabaeid pests are briefly discussed.

A Description of Aphis (Doralis) rumicis, L., and Comparison with Aphis (Doralis) fabae, Scop.

Linnaeus (1746) described a black aphis which he found on Rumex sp. and called it Aphis rumicis. Fabricius (1794) described a black aphis “ Aphis rumicis,” found “in Rumice acuto” and mentioned pale antennae and tibiae. Risso (1826) recorded a species, Doralis rumicis, Leach, found in the Mediterranean region, but did not describe it. Koch (1857) recorded Aphis rumicis, L., from Rumex crispus, feeding chiefly on the stems and flower-stalks. This aphis is also frequently found on thistles and beans. The apterous female has black antennae, white only at the base of the long “ fourth joint.” The wing-pads and thorax of the alate nymphs are olive-green. Kaltenbach (1874) described black Aphids developing from eggs on dock, and having a second winged generation which settles on beans, thistles, Chenopodium sp., and other plants. He observed that the Aphid colonies are on the leaves and flower-stalks. Buckton (1879) gave an illustrated account of a black aphis, Aphis rumicis, L., which has a large number of food-plants including Rumex crispus, Carduus lanceolalus, and broad bean, with furze as its winter host. He noticed the presence of large white flecks on the “pupae.”

AN APTEROUS MUTATION IN BRUCHUS

There appeared in my cultures of Bruchus quadrimaculatus Fabr., the four-spotted cowpea-weevil, a mutation entirely void of wings. It was discovered at Cold Spring Harbor on August 5, I918, in seven females. The wild stocks from which these wingless females emerged had passed through twentyfive generations of selective breeding. This mutation could have only come from a single pair. The culture was obtained from Raleigh, North Carolina, on January I8, I916, and had been examined daily for various mutations. It is known therefore that at no previous time had any such apterous beetles appeared. During the eight years of breeding this insect no more such mutations have been observed among the thousands of weevils examined. The appearance of this Bruchid's wings is not unlike that described by Metz ('14) for apterous Drosophila. Even though the cultures of this apterous insect died out, due possibly to some genital defect, there are some genetic interpretations of value which may be made. This apterous beetle was first discovered in seven females which made their appearance during two days from one wild culture bottle. Because they were the first mutants observed in such great numbers, they were at first thought considered abnormalities or freaks rather than mutations. But when they again emerged in the F2 from apterous females mated with wild males from another North Carolina culture, it was evident that this trait was a recessive one. Concerning the origin of mutations in Drosophila Lancefield ('i8) states that if a mutation occurred in the early oogonial stages several with the new gene should appear. This answers the question why several of the mutants could have been revealed. The fact that they were all of one sex might add evidence to such

An Apparatus for testing the Toxic Values of Contact Insecticides under Controlled Conditions

An apparatus for determining the relative toxicities of contact insecticides is described in detail. It is so arranged that successive batches of insects are sprayed under conditions as similar as possible, so that on using various substances at different concentrations, the results are directly comparable.The apparatus consists of a glass jar in the lid of which an atomiser is fixed. By means of compressed air at known pressure the atomiser throws a constant quantity of fine spray upon insects placed in a dish inside the jar. Photographs illustrating the details of the apparatus are given.The method used in practice for the spraying of aphides in this apparatus is described, and examples are given in the form of a table and a graph of the type of results obtained when different concentrations of nicotine are sprayed upon apterous agamic females of A. rumicis.

The Gipsy Moth, and its Introduction into America

MANY persons, whether entomologists or not, must have noticed a rather slender, dark-coloured moth with feathery antennae flying among bushes on the continent; and a much larger, stout-bodied, whitish-grey moth, sitting on hedges, or on the trunks of trees. Dissimilar as these insects may appear, they are never theless the male and female of the Gipsy Moth (Porthetria dispar), the male of which flies about in the day-time like that of the Vapourer Moth (Notolophus antiquus), a small tawny-brown moth with a white spot on the fore-wings, which has an apterous female, and the caterpillar of which feeds on a great variety of trees and shrubs (Fig. 1).

Societies and Academies

LONDON Entomological Society, October 6.—H. T. Stainton, F.R.S., vice-president, in the chair.—Sir Arthur Scott of Birmingham and Mr. F. E. Robinson were elected as ordinary Members.—Mr. McLachlan stated that last year he had exhibited specimens of Anthocoris nemorum, an hemipterous insect supposed to be damaging the hops grown near Canterbury, but had then expressed his opinion that the insect was not the true culprit, its habits being probably carnivorous. This year he had received from the same correspondent some small larvse which had been found in the cones, and these he considered were not only the true enemy of the hops, but were also the food of the Anthocoris.—Sir Sydney Saunders exhibited a series of apterous females of the new species of Seterodermat adverted to at the previous meeting, and read remarks thereon.—Messrs. Kirby, Fitch, Ralfe, and the Rev. E. N. Gilbert exhibited several varieties of lepidoptera taken in this country and on the Continent, some of which, from the structure of the antennse, were considered “hermaphrodite” forms.—Mr. Hildebrand Ramsden communicated a note on Pyrophorus causticus, a Cuban fire-fly.— Mr. Swinton read two papers entitled Some Experiments on the Variability of Lepidoptera undertaken during the year 1880, and exhibited specimens and figures in illustration.—Mr. Butler communicated a paper entitled Observations on the Lepidopterous Genus Terias, with descriptions of hitherto un-named forms from Japan.—Mr. Waterhouse communicated a paper on the Bupres-tidæ from Madagascar.—Messrs. Kirby, Distant, and McLachlan called the attention of the Society to a method of publishing descriptions of new species pursued by M. Andre in recent parts of his work on European Hymenoptera. These were not only inserted on the cover of his quarterly parts, but even at the end of sheets of advertisements laid loosely between the pages of a part. It was regretted that no other course than that of protest and disapprobation could be applied in the interest of science to such a practice.