BIBLIOGRAPHY

1825. SAY, THOMAS.-Acad. Nat. Sci. Phila. vol. iv. p. 340. Original description. Inhabits Missouri.

1851. FITCH, ASA.-Homop. N. Y. State Cab. p. 57. Describes Gypona flavilineata. 1867. FITCH, ASA.-Trans. N. Y. State Agr. Soc. vol. xxvii. p. 893. (12th Rep.) General account of Gypona octolineata and Gypona flavilineata, which are considered separate.

1873. RILEY, C. V.-5th Rep. Ins. Mo. p. 121. Gives a figure of egg punctures in apple bark, then supposed to be those of Ceresa bubalus Fabr.

1892. RILEY, C. V.-Proc. Ent. Soc. Wash. vol. iii. p. 88. Says that figure of egg pouches given as those of Ceresa bubalus (1873) are those of an allied Membracid, Ceresa taurina Fitch.

1897. OSBORN, HERBERT and BALL, E. D.-Iowa Agr. Exp. Sta. Bul. 34. p. 616. Life history notes. The forms octolineata and flavilineata are considered as the same species.

1900. Lugger, OTTO.-6th Rep. Minn. Ent. p. 135. Affecting blackberry in Minnesota.

1900. FORBES, S. A.-21 Rep. State Ent. Ill. p. 72. Affecting sugar beet in Illinois. 1907. SURFACE, H. A.-Pa. Dept. Agr. Zoöl. Bul. vol. 5. no. 3. Plate IX. Gives an excellent figure of Gypona egg punctures in bark, but refers these to Ceresa bubalus.

1909. WEBSTER, R. L.-Journ. Econ. Ent. vol. ii. p. 193. Mentions finding eggs in an apple, possibly those of Ceresa taurina.

1910. HODGKISS, H. E.-N. Y. Agr. Exp. Sta. Tech. Bul. 17. p. 100. Says that the egg pouches figured by Riley as Ceresa are those made by species of Gypona.

AN UNUSUAL TYPE OF INJURY DUE TO A THRIPS

By J. R. WATSON, Gainesville, Fla.

In the Entomological News for February, 1912, the writer described an apparently new species of thrips (Cryptothrips floridensis), which was attacking camphor trees on the extensive plantation of the Satsuma Company at Satsuma, Florida. Since then some additional studies and a personal inspection of the work of the insect in the field have been made. These studies have discovered a type of injury so unusual for a thrip as to suggest that it might not be without interest to the readers of the Journal of Economic Entomology.

In the beginning of the infestation of the camphor tree, the eggs are laid between the scales of the terminal bud. If the bud has commenced to develop when the eggs hatch, the larvæ first attack the new growth. If there are but a few of the larva on each bud, there will result a blackening and deforming of one side of the young leaves (Plate 11, figure 1). If there are more of the larvæ, the developing bud will be killed outright, (Plate 11, figure 2). The insects then attack the younger twigs where they feed in groups, the yellow larvæ

being very conspicuous on the light green shoots of the camphor. The bark where these groups of larvæ feed is killed (Plate 11, figure 3), and, as it dries out, it cracks (Plate 11, figure 4). The adults use these cracks as hiding places and as a means of entrance to the cambium on which they lay their eggs. As the infestation proceeds the bark on all of the twigs is killed and the leaves are shed. This leaves the cambium as the only suitable breeding place, and here the larvæ as well as the adults are to be found. A favorite feeding place is at the base of a branch. This is quickly killed and then easily broken off, leaving a scar much like the one at the base of a petiole only larger and deeper (Plate 11, figure 5). They also gain access to the cambium at the cut ends of the twigs after the trees have been pruned to supply material for distillation. The Cryptothrips continue to work on the cambium until the whole plant is killed. The insect seems to be incapable of flight, although it has well developed wings. It probably spreads from one plant to another by means of workmen and horses which brush against the plants during cultivation, and by crawling over the ground, leastwise it spreads in all directions from the center of infestation, but most readily along the rows, where the distance between the plants is less than that across the rows. It kills every plant in its onward march, although it may temporarily skip one to attack those beyond.

It was found on large trees at Satsuma, near Palatka, and at Tampa, but seems to do very little harm to them. It is the young seedlings in the nursery row and the young trees in the field that are killed. The writer has been unable to find this insect about Jacksonville, Gainesville, or other towns in north Florida. This raises the question of its origin. The camphor is not a native of Florida. Is this insect a native species which has spread to the camphor, or has it been imported with camphor? The writer will be very grateful if entomologists located where the camphor trees grow will send him specimens. of any black (larval yellow) thrips found on this tree.

Tobacco decoctions kill them, but it has been found necessary to make them stronger than for most species. For the adults a solution composed of a half gallon of whale oil soap, one half gallon of commercial lime sulphur, and a half pound of Black Leaf 40 to fifty gallons of water is now in use. This has proven quite efficient. It does not, however, kill the eggs and of course all the adults and larvæ hidden under the bark escape. By spraying not later than the stage represented in figure 3 when the larvæ are mostly in the buds or on the outside of the twigs, and by cutting out the trees in the later stages of infestation, it was found possible to control this pest.

THE GASOLINE TORCH TREATMENT OF DATE PALM

SCALES

By R. H. FORBES, Director, Arizona Experiment Station

Date palms imported from the Old World into Arizona during the past 23 years have been found generally infested with two scale insects, Parlatoria blanchardi and Phanicococcus marlatti, commonly known as the Parlatoria and the Marlatt scales. These two scales are very highly specialized in their food habits, subsisting so far as yet known only upon the date palm.

Parlatoria blanchardi infests the outer parts of the tree, including leaf stalks, foliage and fruit. Phonicococcus marlatti, however, shuns exposed situations and is found deeply buried between the overlapping bases of the leaf stalks, only rarely appearing where the insects may be seen without digging into the tree. Occasionally, also, the Marlatt scale may be found upon partially exposed date palm roots.

In devising a method for the extermination of Parlatoria blanchardi several years ago the writer, guided by his observation of the Mexican practice of burning date palms to clear them of dead foliage, drenched the trunks of a number of palms with gasoline and set fire to them. The gasoline blast torch was afterwards found to be much more. effective, penetrating inward and downward into the spaces between the leaf bases and thus reaching and exterminating the Parlatoria scale. This method has been in use in the Salt River Valley for the last eight years and this treatment, combined with judicious pruning of the older foliage of infested palms, has been found to accomplish the control of Parlatoria thoroughly and economically.

The Marlatt scale, however, by reason of its deep seated location. in the date palm is not reached and exterminated by a treatment which suffices for Parlatoria. However, by cutting the old leaf stubs of the palm clear down to the bole of the tree, thus largely removing infestations of the Marlatt scale, and by then thoroughly burning the exposed bole of the tree with the gasoline torch, this scale may be entirely removed.

The old Egyptian palms on the Experiment Station Farm near Phoenix, Arizona, thus thoroughly pruned down to the boles and burned in 1906, are found at this time (1913) to be entirely free from Parlatoria and Marlatt scales. On the basis of these observations the following treatment of infested date palms is recommended, and has been adopted by the Arizona Commission of Agriculture and Horticulture: Destroy Parlatoria blanchardi on infested date palms and

their attached suckers by pruning and burning with the gasoline blast torch, as described in Bulletin 56 of the Arizona Agricultural Experiment Station. A year after such treatment, if the tree appears to have been successfully treated, as has proved the case with 90 per cent of those burned in Arizona, the suckers may be cut and transplanted, still infested, however, with Marlatt scale.

When the old tree has ceased bearing suckers it becomes practicable to clean the bole and burn it more thoroughly to eradicate Marlatt scale, the tree or orchard of trees being thus finally freed from both infestations. Transplanted suckers, which at the time of cutting could not have borne the severe burning necessary to deprive them of Marlatt scale, can be followed up in the same way and finally freed of infestation.

SOME RECENT MANUALS OF PARASITOLOGY

By WM. A. RILEY

As a rule the economic entomologist is expected to pass upon all questions of parasitology, whether they relate to insects or other forms. The recently awakened interest in medical entomology has made it more imperative than ever that the student planning to go into work in economic entomology should have a good basis in general parasitology. In this connection, the question as to reliable, up-todate reference-books and compendia is one that frequently arises, and it has seemed that a brief discussion of some of the available texts, with special reference to the latest, would be of help.

Few of the branches of biological science have made more rapid progress during the past few years than has parasitology, and books which were standard until recently, are no longer satisfactory reference books for even those who are not primarily interested in this field. This is especially true of the very phases of the subject which are most intimately connected with the entomological work.

Leuckart's great classic, "Die menschlichen Parasiten," will never lose its value as a discussion of the biological principles underlying parasitism, but it was written years before the pioneer work on the relations between arthropods and parasitic protozoa were suspected and even the discussion of the vermiform parasites is superseded. Moreover, it is long since out of print and the English translation, by Hoyle, is now seldom offered. The work is of such fundamental value that any opportunity to obtain a copy should be seized.

Of the works on this subject of a more econon ie bearing, none has been more widely cited and quoted in this country than has Railliet's