The subject of this paper was selected with enthusiasm. The law of natural compensations seemed most intriguing and the part played by forest insects in its enforcement appeared to afford unusual opportunity for discussion. Now that the time has arrived for its presentation there is a sense of trepidation, because the drawing of generalizations is always dangerous. However, without generalizations we should inevitably be confused by the mass of information concerning populations of insects, their parasites, predators, and host plants, and the responses of these organisms to their habitat. Therefore, it may be appropriate to present this somewhat old story from a different angle to illustrate the viewpoint of one forest entomologist, using some old and some hitherto unreported examples. Most of the examples that will be cited, whether old or new, have been observed first hand.

Attempts to maintain large cultures of the onion maggot, Hylemya antiqua (Mg.), have led to the development of special glass cages (Perron et al., 1953). Under oar laboratory conditions the lights used to obtain the degree of illumination necessary for acceptable oviposition rates raised the temperature and lowered the humidity excessively within the cage. Reasonable control of these factors was obtained by atomizing cold water into a current of air blown through the cage.

Since the monumental work of Rose (1938) on the essential amino acids for growth in the rat, similar studies have been made on other vertebrates. It has been shown that most of these animals have the same pattern of amino acid requirements for growth of the immature form and for maintenance of nitrogen equilibrium in the adult. The amino acids usually required are arginine, histidine, isoleucine, leucine, lysine, methionine, phenylalanine, threonine, tryptophane, and valine. These studies have been adequately reviewed in recent texts (Bourne and Kidder 1953, Albanese 1950).

As mentioned by Morris (1942), the forest entomologist is frequently faced with the practical problem of ascertaining the identity of certain insects which have defoliated the trees and disappeared before his arrival. Cast skins and head capsules provide a difficult and uncertain means of identification; and the kinds of damage done by the insects often are alike to such an extent that they are non-specific. There remains the abundant fecal pellet deposit, commonly called frass, which, if studied carefully, is a reliable means of identifying many species.

In extensive surveys for parasites of Hylemya brassicae (Bouché), H. floralis (Fall.), and H. cilicrura (Rond.) on cruciferous crops in Canada and Europe, observations were made on the life-histories and behaviour of the parasites. Accounts of the two most abundant parasites, Aleochara bilineata Gyll. and Trybliographa rapae (Westw.), have already been published, the former by Colhoun (1953) and the latter by Wishart and Monteith (1954). The present paper deals with one of the minor parasites, Phygadeuon trichops Thoms. In the surveys this parasite was found in Norway, Holland, and Scotland but in such small numbers as to indicate that it has other, preferred hosts and that it only occasionally attacks Hylemya spp. Phygadeuon fumator (Grav.) was reared from Hylemya sp. from France and is recorded in the literature from Hylemya spp. in Russia (Meier, 1927; Vodinskaya, 1928) and in England (Wadsworth, 1915). No references were found to P. trichops from Hylemya spp. and no accounts of the biology of either species.

The most recent list of the North American species of Orenaia was given by McDunnough (1939: 14), who referred two species to the genus. In the present paper two nominal species are transferred from Titanio to Orenaia, one as a synonym, and a new species of Orenaia is described.

Titanio and Orenaia agree in the reduced eyes, stout build, hairy vestiture, and noctuid-like facies. However, as was first shown by Müller-Rutz (1929), the genitalia of Orenaia are indistinguishable from those of Evergestis, whereas those of Titanio are of a very different type. The similarity in habitus of the two genera is undoubtedly the result of convergence.

In June, 1955, a spider collected at Harrow, Ontario, May 28, 1955, by Mr. Robert Walsh of the Science Service Laboratory there, was sent to the author for determination. This specimen proved to be a mature male of the species, Atypus niger Hentz, commonly known as a “Purse-Web” spider. Subsequently, Dr. Willis J. Gertsch, of the American Museum of Natural History informed me that several years. ago he determined a female of Atypus niger found at Grimsby, Ontario (1). This specimen was collected on July 12, 1942, by Wm. L. Putman, of the Science Service Laboratory, Vineland, Ontario. Apparently Mr. Putman's specimen represents the first of this species to be taken in Canada. I am indebted to Dr. Gertsch for his kindness in making this information available for use at this time.

The oviposition behaviour of numerous parasites toward hosts already parasitized has been the subject of a considerable number of investigations during the past twenty years. Many species of ichneumonids, braconids and chalcids have been shown generally to avoid oviposition in parasitized hosts under laboratory and field conditions but there are conflicting views on the nature of this behiviour and on the cause for such rejection (Salt 1935, 1937, Ullyett 1936). Incomplete data hearing on these problems with the parasite Mastrus carpocapsae are given here. Dificulties in laboratory propagation and particularly irregular and erratic oviposition under the experimental techniques employed have prevented a fuller study; hut it is felt that the data will be of interest to workers in this field of behaviour since in certain respects the findings help in the interpretation of relevant facts demonstrated in previous investigations.

In 1937 Schwarze and Huber (3) reported the variety of Rubus idaeus L named “Lloyd George” to be totally resistant to the aphid Amphorophora rubi Kalt. This fact was of some economic significance because the aphid in question had been shown to be an active vector of Rubus viruses in North America. It was suggested that the aphid-resistant qualities of Lloyd George should be incorporated in plant-breeding programmes with a view to producing hybrids, with desirable commercial qualities, which would escape infection by the viruses.

On June 20, 1950, aphids were collected from grass on the Tantramar marshes at Middle Sackville, N.B. The aphids were causing serious damage and turning the grass brown. The writer was unable to place the aphid in a genus according to Hottes and Frison (193l), Gillette and Palmer (1931), or Baker (1923). However, according to Baker (1920) and Theobold (1929) the aphid would fall in the genus Atheroides Haliday, on the basis of the shape of the cauda. It differed from the descriptions by Laing (1920) and Baker (1920) of the genus Atheroides in that the cornicles were prominent. In February, 1955, several specimens of the aphid were sent to Mr. J. P. Doncaster, British Museum of Natural History, who (in litt.) determined the specimens as of Sipha agropyrella (H.R.L.). Dr. Hille Ris Lambers, Bennekom, Holland agreed (in litt.) with this determination.