baskets loaded with fruits and vegetables makes a house to house canvass and offers, often badly infested, fruit for sale. These Chinamen will take orders for large amounts of fruits and deliver the same to your door. How easy it would be for the unthinking, traveling public to buy fruit from these peddlers and pack the same in a trunk to take to their friends or for their own use on the mainland!

PRESIDENT W. D. HUNTER: Is there any discussion on this paper? MR. C. L. MARLATT: I am very glad to have listened to Mr. Severin's paper and I think he is correct in many things that he has said, but he is a little behind the times as to some things and he is not altogether fair in speaking of control measures. I spent one month in Hawaii and during that time I was very busy seeing all that was possible of the fruit fly throughout the islands of Hawaii. Human effort is never perfect. Nursery stock is sent to every place in the United States and the success of the Federal Plant law depends on the individual inspectors. A law rests on the character of the individual who enforces it. The authorities in Honolulu have undoubtedly done the best they could. When I was there the city was as clean as a dollar and there was no affected fruit noticeable. It is true, there was not much fruit when I was there, and the season that Mr. Severin speaks of is the season when the fruit is most abundant, when hundreds of barrels fall from the trees every night and the conditions are necessarily at their worst. No doubt the conditions when Mr. Severin was there are correctly described but somewhat wrongly interpreted. The inspection at the San Francisco end is a further check, and the fruit is prohibited at British Columbia. The protection elsewhere along the coast is pretty good. If there is a single bad or broken fruit the inspectors at San Francisco reject it. You can find good and bad in any question, but in this instance the balance is distinctly on the right side. The experimental testing of food products is to be very carefully done, and if we find that there is danger from bananas the federal quarantine will be extended to this fruit. California has not been lenient in letting things in; she has rather gone to the other extreme and carried her quarantines beyond the actual needs. Bananas and pineapples are inspected now by federal officers in Hawaii, and that inspection is repeated at San Francisco. No doubt it is true that some officers have not been absolutely above suspicion, but that is one of the things we have to come in contact with always in human nature. The paper points out one side rather than the other. We are improving the situation as fast as we can, and I think the people who have been affected by this quarantine have accepted it with splendid spirit. There has not been a bit of hesitation in establishing safeguards, and

I think there is a good deal to be said in commendation. The work that Mr. Severin did is much to his credit, but you cannot blame people for resenting criticism when they are doing the best they can. I am sorry that Mr. Severin's work was interrupted. It was very interesting and has added much to our knowledge of the fly.

PRESIDENT W. D. HUNTER: The next paper will be presented by Mr. C. H. Hadley, Jr., on "A City's Attempt to Trap Brown-tail Moths."

A CITY'S ATTEMPT TO TRAP BROWN-TAIL MOTHS

By C. H. HADLEY, JR., Durham, N. H.

(Paper not received for publication.)

MR. F. L. WASHBURN: I should like to have you give some data on the relative number of male and female noctuid moths, which came to the lights.

MR. C. H. HADLEY, JR.: We secured no data on the number of noctuid moths.

MR. A. F. BURGESS: In connection with the data given in this paper I will say that during the summer of 1910 a series of experiments was conducted in Reading, Mass., for the purpose of determining the percentage of male and female brown-tail moths that could be trapped at are lights. In all thirteen separate lights were used and the experiments were carried on throughout the month of July. A considerable variation occurs in the number of the sexes secured during different times in this month. In 1910 the first moths were caught July 1 and the last ones July 29. Over 78,000 were secured and these were preserved and carefully examined during the winter; 71 per cent. of the insects were males and of the females only 2 10 per cent. had deposited their eggs. At these trap-lights large numbers of other insects were secured. An interesting feature was that a very large percentage of the female tent caterpillar moths, that were secured in the traps, had already deposited their eggs. I cannot give the relative percentage. of male and female noctuid moths which were obtained, although I think we have some data on this subject.

MR. P. J. PARROTT: Is this trap considered a promising method for general use?

MR. A. F. BURGESS: Most of the traps which we used consisted of a pan in which was placed water and a small amount of oil. The labor of cleaning these every day was considerable and we did not think they were a practical method of control.

February, '13] BURGESS & ROGERS: GIPSY MOTH FOOD PLANTS

75

PRESIDENT W. D. HUNTER: The next paper, "The Results of Experiments in Controlling the Gipsy Moth by Removing its Favorite Food Plants," will be read by Mr. A. F. Burgess.

RESULTS OF EXPERIMENTS IN CONTROLLING THE GIPSY MOTH BY REMOVING ITS FAVORITE FOOD PLANTS

By A. F. BURGESS and D. M. ROGERS, Boston, Mass.

For many years great effort has been made to bring to perfection the mechanical methods for controlling the gipsy moth. Aside from the work of introducing the parasitic and predatory enemies of this insect, experiments along the line of perfecting methods of control have occupied a great share of the attention of the government and state officials in charge of the moth work and of various investigators and observers connected with it. In the earlier writings concerning the feeding habits of gipsy moth caterpillars and in the experiments which were conducted to test their ability to feed on the foliage of the native tree growth of New England, the conclusion was reached that this insect was a general feeder and that practically all the trees or plants concerned would suffer severe injury on account of being defoliated by the larvæ. In fact, during the period when the territory in the suburbs of Boston was the worst infested, about the years 1904 to 1906, large woodland areas were completely defoliated owing to the enormous number and voracity of the caterpillars.

Early in 1907 it was noticed that in many places, where the gipsy moth defoliation had been severe, that the larvæ seemed to show some preference in the species of trees attacked. It was also observed that white and pitch pine did not appear to be severely defoliated unless they were growing in or near an area of hardwood trees. Realizing the importance of this matter Mr. A. H. Kirkland, then superintendent of the Moth Work for the state of Massachusetts, detailed Mr. F. H. Mosher to carry on a series of laboratory experiments to test the feeding of newly hatched gipsy moth caterpillars on pine foliage. These were carried on during the spring of 1907 and were repeated the following spring. Mr. Mosher failed to rear first stage caterpillars on this food. In the spring of 1908 an extensive field test was made, using a clear stand of about five acres of white pine growth in Arlington, Mass. This experiment was carried on coöperatively between the Massachusetts superintendent of Moth Work and Mr. D. M. Rogers of the U. S. Bureau of Entomology. The locality was badly infested and the trees on the border about 100 feet deep, were banded with tanglefoot in order to prevent caterpillars from crawling into the

area. No other treatment was applied and no injury resulted to the

trees.

During the following two years observations were made on the feeding habits of the gipsy moth caterpillars by various observers, and in 1910, when bulletin No. 87 of the Bureau of Entomology was published, covering a report of the field work against the gipsy and brown-tail moths, enough information had been secured so that the authors felt warranted in making the following statements.

On page 14 it is stated that the gipsy moth has a varied list of food plants, "in fact, it will eat almost any kind of vegetation, although it seems to prefer the foliage of oaks, willows, and apple trees. Repeated observations have shown that the ash, juniper, and red cedar are practically immune from attack, while the maple is not injured to any great extent if more desirable food is within easy reach." As a result of these observations it was recommended, pages 73 and 74, that "owners of woodland on which the trees are of marketable size should cut the timber if the gipsy moth is prevalent in the region. Care should be taken in doing this work to cut out all poor and worthless trees, and if possible to leave for reforesting purposes, vigorous specimens of ash, maple, pine, or coniferous trees of which the insect is not especially fond and which can be protected with the least possible expense. The planting or preservation of ash and hickory is recommended as the wood is of high value and these trees are not subject to attack by the brown-tail moth. Planting pine or other coniferous trees for reforesting purposes is also advisable, as the region is suited to their growth and these can be protected from moth injury at slight expense. It is probable that many of the forests containing oak or other trees which are preferred by these insects must in time give way to species less subject to attack. In the meantime the owner should take advantage of the opportunity to harvest. his merchantable trees that are susceptible to attack and foster the growth of other species that will not be destroyed.”

After the publication of this bulletin more observations were made on the food plants of the gipsy moth and Mr. Rogers became so thoroughly convinced of the practical utility of eliminating the trees, which were most favored by this insect, that in the winter of 1910 11 much consideration was given to the subject by him and several experiments were carried on, on a large scale to determine what would happen if forest areas were thinned to solid blocks of species which had frequently been observed to withstand defoliation.

An area was selected near Chelmsford Center, Mass., where the tree growth was chiefly chestnut, with some gray birch and oak, and where the infestation was heavy. Seven acres were used for the

experiment. The oak and all other trees, except chestnut, and a few conifers, were removed and the brush and slash burned. This left a stand of chestnut trees averaging 35 to 45 feet in height, all of which were badly infested. No detailed observations were made during the early summer, but occasional visits by Mr. Rogers during the season failed to indicate any defoliation of the chestnut trees. Since that time the brush and sprouts have been allowed to grow and while the trees have not been injured by caterpillar feeding, the oak sprouts have furnished enough food so that the infestation is slightly greater than it was in the fall of 1911.

During the same winter another block of woodland in Methuen, Mass., covering about twenty-five acres, was thinned as an experiment. One section of this woodlot covering perhaps four acres consisted mainly of white pine with scattering oak trees and undergrowth; the balance consisting of red and white oak, gray and yellow birch and red maple. The latter species was particularly common on the low ground and in some parts of this area several small groups of hemlock trees were growing. The section where pine predominated was thinned to solid white pine growth, while in the oak and maple area all the oaks were cut except a few specimen trees. On the lower land all oaks and birches were removed leaving red maple, and in a few places hemlocks and an occasional pine. A part of the trees growing on the high ground was badly infested and the infestation decreased slightly on the lower ground where more maples were growing. In the spring of 1911 the trees on the higher area were banded with tanglefoot, where this lot joined a badly infested woodlot, but no other treatment. was applied and no serious injury resulted except to some of the oaks. The infestation over the entire area decreased remarkably as a result of the thinning. This fall, 1912, practically all of the trees, except the oaks, are in good condition. A slight infestation can be found throughout the entire area but it is apparent that no injury to the trees is likely to result from it. This woodlot has been used as a pasture for cattle so that very little sprout growth exists.

In order to follow up the results of making experimental thinnings and to attempt to secure more information on this important phase of the gipsy moth work, as well as to obtain field data which could be used in connection with an extensive series of laboratory feeding experiments, which were made during the summer of 1912, a number of areas were thinned during the winter of 1911-12 under the direction of the writers.

In Hudson, Mass., an area of chestnut, maple, red and white oak, gray birch and ash, with various kinds of undergrowth which was slightly infested, was thinned to a chestnut stand and all specimens