One of the objects of the investigations on the European spruce sawfly, Gilpinia hercyniae (Htg.), in Eastern Canada was to discover and evaluate the factors of natural control affecting this introduced species in its new environment. Small mammal predators were found to be the most important factor affecting the sawfly cocoons, which were spun in the moss or litter of the forest floor (4, 5). These predators chewed large openings in the cocoons and pulled out the contents. Cocoons were also found with smaller openings made by the entry of insect predators, and occasionally such a cocoon was found with a larva of the family Elateridae partly inside (Fig. 1).

There are many types of commercial photo copying machines designed to make paper negatives or direct paper positives without the aid of a camera. These range from the costly rotary printers used in industry to the cylindrical type used in offices. Most of these produce excellent copies of single sheets; but with many of them there is considerable difficulty in making copies from books, the printing usually being blurred and the copy unevenly shaded. The physical pressure required to make perfect contact during exposure often damages larger books.

Several ecological factors governing populations of the larch sawfly, Pristiphora erichsonii (Htg.), have been studied in Manitoba and Saskatchewan since the present outbreak began about 1939. It soon became clear that soil moisture, parasires and predators, and the growth habits of tamarack were among the most important components of the environmental resistance. Data from ohservations and experiments were gathered by several investigators of the Forest Insect Laboratory, Winnipeg. Manitoba, and are still largely unpublished. In this paper, an attempt is made to appraise the over-all effect of these factors on abundance of the larch sawfly.

As the flea fauna of mammals of northern North America becomes better known, its very close affinity with that of temperate and northern Asia becomes more apparent. Many of the genera are holarctic and are associated with holarctic genera of mammals. In a few instances, the fleas of the Old World and the New World are so similar in morphological details and host association that they are regarded as subspecies. For example, Amphipsylla sibirica (Wagner), Malaraeus penicilliger (Grube), Megabothris calcarifer (Wagner), and Hoplopsyllus glacialis (Taschenberg) have representatives in both the nearctic and the palaearctic regions. To this list must now be added Catallagia dacenkoi Ioff, a parasite of Microtinae; this species was described originally (Ioff, 1940, pp. 216-217) from the Altai Mountains of central Russia, and a new subspecies has now been discovered in northern Canada and Alaska.