O'Kane, W. C. Injurious Insects, pp. 150-151, 1912. Quaintance, A. L. 383, 1912. Bulletin No. 45, Georgia Agr. Expt. Station, 1899. Sirrine, F. A. Bulletin No. 158, New York (Geneva) Agr. Expt. Station, May, 1899. Smith, R. I. Bulletin No. 205, North Carolina Agr. Expt. Station, 1910. THE IMPORTED PINE SAWFLY. Diprion (Lophyrus) simile Hartig. By W. E. BRITTON and M. P. Zappe. This European pine sawfly was first discovered in this country at New Haven, Conn., in August 1914, by the writers, who, in company with Mr. Irving W. Davis, were inspecting the stock in one of the nurseries. The larvae were feeding upon the leaves of pine trees. As the inspection work continued for several days, we later found the larvae more abundant in another part of the nursery and considerable material was gathered and taken to the laboratory. Though unfamiliar, we supposed this to be a native, and perhaps not uncommon species. A portion of the collected material was sent to Dr. Alexander D. MacGillivray of the University of Illinois, who was engaged in the study of sawfly larvae, and who at that t'me had finished preparing the manuscript of the Tenthredinoidea for the publication entitled The Hymenoptera of Connecticut, which has since appeared as Bulletin No. 22 of the Connecticut State Geological and Natural History Survey. Dr. MacGillivray was unable to identify the larvae but thought that he might recognize the species if the adults could be obtained. The larvae in the breeding cages matured in due season and made their cocoons. From this material the first male emerged on April 8, 1915, followed by others, and on April 15 the first female appeared. Males and females were placed in cages containing potted white pines and the females soon laid eggs. On April 21, we wrote to Dr. MacGillivray, informing him of the emergence of the adults. He examined his own cages and found that the adults had emerged there also. He replied that they belonged to the genus Diprion, formerly known as Lophyrus, but that he did not recognize the species, several of which are badly confused; that Mr. S. A. Rohwer of the Bureau of Entomology at Washington, D. C., was trying to straighten them out and had already examined many of the types in the British Museum. He suggested that specimens be sent to Mr. Rohwer. IDENTITY. Following Dr. MacGillivray's suggestion, on May 6 material was sent to Mr. Rohwer, who soon replied as follows: "I have determined this species, tentatively, as Diprion simile Hartig. The adults agree more closely with those in the collection under the name pini but the larvae answer exactly the description of simile, and as these two species are very closely allied and easily confused in the adults, I have made the determination from the larvae rather than from the adults. "This species is one of the most injurious sawflies on European conifers and has been associated in practically all of the depredations caused by pini, and is recorded in the literature in a number of cases under the name of pini. You are, no doubt, familiar with the economic importance of Diprion pini in Europe. It is highly important that immediate measures be taken to combat this injurious insect as it has a large number of host trees and would no doubt adapt itself readily to the conditions in America, where, if it were thoroughly established without its parasites, it would do a great deal of damage.” Though two and one-half years have elapsed since Mr. Rohwer made this identification, and as he has studied the life history and food habits of the species from material furnished by us, a recent communication states that his subsequent observations serve to confirm his tentative identification. We may, therefore, consider it to be fairly well settled that this sawfly is the European Diprion simile Hartig. Some of the European writers place simile as a synonym of pini, but Dr. Enslin and certain other European specialists, as well as Mr. Rohwer, who has studied the species carefully from American and European material, consider them distinct. PUBLICATIONS FROM THIS DEPARTMENT. A brief account of the discovery of this insect in the United States was prepared with the help and approval of Mr. Rohwer, and this article, with a plate of illustrations, was published in the Journal of Economic Entomology, Vol. 8, page 379, June, 1915. A note, with figure of larvae, was also printed in Tree Talk, Vol. 3, page 45, November, 1915. A more complete account, or at least complete at the time, of our observations on this insect was given with bibliography in the Report of this Station for 1915, page 118. This paper was illustrated by three plates (vii, viii and ix). A brief paper, "Further Notes on Diprion simile Hartig," was prepared to be presented to the Columbus, Ohio, meeting of the American Association of Economic Entomologists in December, 1915, but in the absence of the writer this paper was read by title, and printed in the Journal of Economic Entomology, Vol. 9, page 281, April, 1916. These papers just mentioned were all prepared by the senior author. At the New York meeting of the American Association of Economic Entomologists in December, 1916, Mr. Zappe read a short paper entitled "Egg-laying Habits of Diprion simile Hartig," which paper appeared in the Journal of Economic Entomology, Vol. 10, page 188, February, 1917. Since the publication of these papers some additional information has been obtained and all have been brought together in the present paper. DISTRIBUTION IN CONNECTICUT. Though first discovered in New Haven, this insect was soon found in Derby, Hartford, Greenwich and New Canaan, five separate towns, and three distinct and rather widely separated regions in the State. DISTRIBUTION IN THE UNITED STATES. Diprion simile has now been recorded not only from Connecticut but also from the states of New York and New Jersey, where it was discovered in 1916. In New Jersey it is known to occur at South Orange, Elizabeth and Rutherford.* In New York it has been taken at Flushing, Long Island. In Connecticut, Massachusetts, Pennsylvania, New Jersey, Indiana, and doubtless in other states, cocoons have been found on imported nursery stock coming from Europe. *H. B. Weiss, Journal of Economic Entomology, Vol. 10, page 224, February, 1917. DISTRIBUTION AND DAMAGE IN EUROPE. This sawfly is mentioned in literature as occurring with pini† and therefore responsible for a portion of the damage. In most cases, however, the serious injury is accredited to pini, which has seriously damaged the pine forests of Southwestern Russia, especially the young trees; pini was particularly destructive in France§ in 1906, and has also caused damage in Prussia and in Sweden. In England it is said to injure Scotch fir as well as pine. ** In 1914, larvae of pini nearly defoliated the ten-year old pine trees on one plantation in Norway. The insect was reported from many localities. During the same year pini denuded many acres of pines in the districts of Achtyr and Izium in Russia, and caused much damage in Germany, particularly in Brandenburg and Silesia. A INJURY TO TREES. The injury consists in defoliation. The older and mature leaves, instead of the newly-formed ones, are eaten. In late summer the new growth may serve as food for the second brood larvae, so that in this manner the larvae when abundant are able to entirely defoliate trees. Plate VII, b, shows a tree of Pinus cembra about seven feet tall almost stripped by the larvae in 1915. Formerly it was supposed that a pine in this condition would not recover. In spite of the fact that the needles were eaten off, the buds were formed for the next season's growth, and the tree put out leaves in 1916 as usual, and as this foliage was protected by spraying, the tree did not seem to be permanently injured. If the tree had not been sprayed and the larvae abundant, the second brood larvae would doubtless have stripped it † Kaltenbach, Die Pflanzenfeinde, page 700, 1874. Judeich-Nitsche, Forstinsektenkunde, page 635, 1895. Review of Applied Entomology, Vol. 1, pages 395 and 493, 1913. § A. Barbey, Traité d'Entomologique Forestière, page 269, 1913. W. E. Collinge, A Manual of Injurious Insects, page 217, 1912. E. A. Ormerod, Manual of Injurious Insects and Methods of Prevention, page 250, 1890. ** Schoyen, T. H., Review of Applied Entomology, Vol. iv, page 503, 1916. Ibid, Vol. iii, page 443. ▲ Ibid, Vol. iv, page 3. again, and if stripped for a few consecutive seasons, it would surely be killed. According to the published accounts, in Europe the injury seems to be confined to young trees up to twelve or fourteen years of age. LIFE HISTORY AND HABITS. There are two broods each year in Connecticut and the winter is passed in the cocoon on the twigs. The adults begin to emerge in April and continue through May and up to July 20. Meantime most of the first brood larvae had matured and made their cocoons by the middle of June. The second brood larvae feed during August and September. Thus it will be seen that these broods are not well separated but overlap so that it is often difficult to distinguish them. The larval stages, on the average, last about 30.5 days. The larvae of the first brood feed upon the old and mature leaves and leave the tender new growth untouched. This new growth becomes sufficiently mature, however, to be used as food by the second brood larvae. In our studies, nearly all of the cocoons of both broods are fastened to the twigs, but in Europe it is said that the first brood cocoons are so placed, and those of the second brood are found upon the ground. The larvae feed with their heads toward the tip of the needle as shown on plate VI, and when very young often three or four together surround it. When feeding in this manner they eat all of the needle, but when only one or two feed they eat along the edge of the needle, making it look as though it had been scraped. When the larvae are disturbed they throw their heads back, and from their mouths exude a drop of liquid which they absorb again. The full grown larvae, in looking for a suitable place to spin cocoons, occasionally crawl into an empty cocoon which is still attached to the tree. Then all that is necessary is to put a new Such a case is shown on plate IX, b. top on the old cocoon. NUMBER OF Broods. In Connecticut there are two broods (considering a brood from adults to cocoons) and in 1915 a partial third brood was obtained. The adults emerging from the second brood cocoons in this case |