. An annotated list of the important North American forest insects. Forest insects. Washington, D. C. T December 12,1923 THE IMPORTED PINE SAWFLY/ By William Middleton, Scientific Assistant, Forest Insect Investigations. CONTENTS. Faee. Introduction 1 Deseriptions 1 Life history and seasonal history 7 Effect of meteorological conditions 14 Parthenogenesis 15 Page. Parasites 16 Hosts 17 Distribution in the United States 20 Economic importance 20 Control 21 INTRODUCTION. A European insect, the imported pine sawfly,^ has recently been found defoliating young pine trees in nurseries and on estates
. An annotated list of the important North American forest insects. Forest insects. Washington, D. C. T December 12,1923 THE IMPORTED PINE SAWFLY/ By William Middleton, Scientific Assistant, Forest Insect Investigations. CONTENTS. Faee. Introduction 1 Deseriptions 1 Life history and seasonal history 7 Effect of meteorological conditions 14 Parthenogenesis 15 Page. Parasites 16 Hosts 17 Distribution in the United States 20 Economic importance 20 Control 21 INTRODUCTION. A European insect, the imported pine sawfly,^ has recently been found defoliating young pine trees in nurseries and on estates in cer- tain of the New England and North Atlantic States. This bulletin contains descriptions of the principal stages of the species and some information on its life history, host plants, distri- bution, and importance, together with a brief discussion of its control. The data presented are based on investigations of the sawfly con- ducted at tlie eastern field station of the Forest Insect Investigations, Bureau of Entomology, at East Falls Church, Va. The studies began with the receipt of material in August, 1915, and continued until the spring of 1919, when the last adults emerged in the cages. Inasmuch as the species was an introduced and dangerous one which had not become well established in this country, great care was exercised in the cage work, in order to prevent its escape. A special double-waUed, screen-wire insectary was constructed to which en- trance was had only through a vestibule, and all the experiments were performed on yoimg trees transplanted into this inclosure. DESCRIPTIONS. The following descriptions have been prepared, so that this species can be recognized in its principal stages. Those of the adult are by S. A. Rohwer. ' This bulletin was prepared under the direction of S. A. Rohwer, to whom the author is indebted for many helpful suggestions in conducting the investigations. The descriptions of the adult insects are by Mr. Rohwer. The majority of th
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