room continued to oviposit for a week, scattering their eggs over the bark, some in cracks, some under the edges and some on exposed situations; also that 533 eggs were taken from the abdomen of one female.

On October 15, 1924, the males were quite abundant around electric lights, and several were collected. They did not disappear at once but were seen on warm nights through the remainder of October and November. Mr. Rogers spent some time looking over trees but did not find any females. The writer collected three females from the trunks of woodland trees, November 20, in Macedonia State Park, Kent.

The Station collection contains males collected by the writer in New Haven, 25 November, 1905; 7 November, 1906; 15 October, 1924. Two specimens from Pemaquid Point, Me., collected in August, 1906, by Professor H. W. Foote are also in our collection.

DESCRIPTIONS.

Egg: Cream color, shape somewhat cylindrical, bluntly rounded at the ends. The sides and one end where the cap is situated are marked with compressed hexagonal reticulations, most pronounced on the cap. Laid singly or sometimes in loose clusters generally attached by one side. Length about .9 mm., width about .52 mm. The eggs are shown on Plate XXX, c.

Larva: A bright yellow looping caterpillar with rust-brown head and ten crinkled black lines extending longitudinally along the back. There is great variation in width of these lines, so that the dorsal view of some caterpillars is nearly black, and others are distinctly light-colored. The outer black line or stripe is often heavier or more pronounced than the others and is wavy, giving a scalloped appearance to the margin. The under surface is yellow and paler than the yellow between the black lines. Legs and prolegs yellow. Length of mature larva, nearly 1.5 inches. See Plate XXX, d.

Pupa: The pupae are brown, slightly more than half an inch in length and rather stout, though the females are somewhat shorter and thicker than the males. The pupae of both sexes terminate in a sharp point.

Adults: Male, forewings buff, marked transversely with two wavy brown bands, and sprinkled with fine brownish dots; rear wings, lighter buff or nearly white with no prominent markings. Scales of head, thorax, abdomen, and legs and antennae about the same tint as ground color of forewings. Wing-expanse about 1.75 inches.

Female, wingless, greenish-yellow, varying to light gray or brown, with two rows of black spots on the back. Legs and antennae are ringed with black and yellow or the ground color. Length about half an inch.

Both sexes are shown on Plate XXX, a and b.

METHODS OF CONTROL.

The best means of control is to spray the foliage in May with lead arsenate as is done for canker worms. The poison may be applied as soon as there is sufficient foliage to hold the poison. If applied too early, other leaves will put out upon which the caterpillar may feed and two sprayings may be required. If applied too late, considerably injury will result before the caterpillars are killed. In the average season, about the middle of May will probably be the best time. From three to five pounds of powdered lead arsenate per 100 gallons of water may be used, and if one pound of caseinate spreader is added, it will be possible to give a better coating to the foliage.

LITERATURE.

1 Britton, W. E., Report Conn. Agr. Expt. Station, page 184, 1915. 2 Felt, E. P., 30th Report, New York State Entomologist, page 59, 1914. Schoene, W. J., New York (Geneva) Agr. Expt. Station, Bull. 423, page 376, 1916.

Slingerland, M.V., and Crosby, C. R., Manual of Fruit Insects, page 89, 1914.

SUBSTANCES ATTRACTIVE TO THE CABBAGE

MAGGOT FLY.

R. B. FRIEND.

The experiment described below was carried on at the Experiment Station Farm, Mount Carmel, in the spring of 1924 for the purpose of finding some substance which would attract adult females of the cabbage maggot (Hylemyia brassicae Bouché) before oviposition occurred. This fly lays its eggs just below the surface of the ground close to the stem of the young cabbage plant. Believing that the odor of the cabbage plant would be attractive to the flies, especially if combined with some sweet substance, materials were tried which contained extracts of the cabbage plant or pieces of the plant itself. In view of results obtained by the New Jersey Station with a honey and yeast mixture in attracting the adults of H. ceparum, this medium was used extensively in our experiments. The following mixtures were tried over periods of varying length, the number of trials depending on the promise shown by the bait.

1. Residue from distilled extract, honey, yeast and water. 2. Pieces of cabbage, honey, yeast and water.

3. Pieces of cabbage, molasses, yeast and water.

4. Brown sugar, yeast and water.

5. Extract of the cabbage plant.

6. Residue from distilled extract.

7. Extract of the cabbage plant and ground charcoal.

8. Honey, yeast and water.

9. Molasses, yeast and water.

10. Pieces of cabbage, brown sugar, yeast and water.

The extract of the cabbage plant was prepared by grinding the entire plant in a food grinder, adding to this an amount of 95 per cent. ethyl alcohol in cubic centimeters equal to the weight of the cabbage in grams (this amount was sufficient to cover the ground cabbage) and letting this mixture stand at room temperature a week. It was then filtered in a press, and the resulting clear alcoholic extract distilled under reduced pressure at bath temperature of 65°-75° C. to about one-twentieth of the original volume. Most of the odoriferous substance apparently remained in the residue. Any reference to extract refers to the filtered but not distilled alcoholic extract, and references to residue refer to the residue left after distilling the extract.

The material in each trial was placed in the pan of a Hodge fly trap and kept from drying by the addition of water. About five grams of honey, molasses or sugar was used with enough water for 60 cc. About 20 cc. of residue was used, and when yeast was used, a cube five millimeters thick was found sufficient. The extract was always used pure. If pieces of cabbage were used, five or six pieces of leaf about 2 cm. square were added. In the trials with charcoal, two teaspoons of ground charcoal were added. The traps were set on the ground and in the rows between plants, being about twenty feet apart. The cabbage plot contained three rows of plants and was about 200 feet long. Examination of traps was made each day, the flies killed and removed, and water was added if necessary. One of these traps is shown on Plate XXXI, a.

The experiment was carried on from May 20 to June 10, and Table I gives the results obtained. These figures are totals of five species of the genus Hylemyia, H. brassicae Bouché, H. ceparum Meigen, H. cilicrura Rondani, H. cinerella Fallen, and H. trichodactyla Rondani, of which cinerella and ceparum probably do not attack the Cruciferae. It will be noticed that between May 22 and May 27, when conditions were similar for all materials then tried, that the residue-honey-yeast-water formula proved by far the most attractive, and the cabbage-yeast-molasses-water formula was next, although the difference between the latter and the molasses-yeast-water formula was insignificant. If the table is examined carefully and the dates noted, it will be apparent that the residue-honey-yeast-water formula is far superior to any other tried. The addition of yeast in quantities sufficient to form a noticeable ferment was of distinct value, as without this the materials were much less attractive. Other baits tried but found of little value were mustard oil (allyl isothiocyanate), allyl alcohol, ethyl alcohol, methyl alcohol, isopropyl alcohol, butyl alcohol, honey, brown sugar, water, and yeast. These were used with water in all cases. The addition of charcoal removed the attractiveness. The residue in itself was by no means as attractive as when mixed with yeast and honey.

The durability of the attractiveness of the materials was observed, and Table II gives these figures. The residue-honeyyeast-water formula was by far the most durable and the pure extract the least. The volatility of the alcohol in the extract rendered it unattractive after a day. This was also true of the alcohols tried. In one instance the residue-honey-yeast formula remained attractive two weeks with the addition of water only. In Table II, the dates begin at May 16, as four traps were set on that date, although the main part of the experiment did not begin until May 20. As soon as any yeast bait became dry, the yeast died and had to be replaced. The need of sugar as food for yeast is obvious, and the sugars are, of course, attractive in themselves.

The total number of flies of all species caught was 1,841 females and 583 males, and the greatest number in any one day was 70 with the pure extract on May 23, and 61 with the residue-honeyyeast-water formula on May 27. An estimation based on a determination of 348 individuals taken at various times in the course of the experiment indicates that 68 per cent. of the females and 76 per cent. of the males were H. cilicrura and only five per cent. of the females and two per cent. of the males were H. brassicae, these two species being the ones with which we were most concerned. The relative extent to which these species attack cabbage is not known. A warm bright day gave more flies than a day that was cool or cloudy. The occurrence of rain gave little trouble with the baits, as the wire of the traps protected the pans and prevented an overflow. The traps were staked down to prevent the wind from turning them over. A change in the relative position of the traps indicated that this factor was negligible. The plot sloped but little and conditions were uniform in this respect. The great predominance of females over males might have been due in part to the odor of the cabbage plant, the females being attracted to this plant to oviposit. Several females were examined for eggs, and of those examined 75 per cent. contained eggs in varying stages of development, the number of eggs per female running up to 44. In a series of similar experiments with the onion maggot (Hylemyia ceparum) all the females were examined each day, and eggs were found in from 76 to 91 per cent. of the individuals. There is no doubt but what most of the flies caught were females, and of the females, the great majority had not finished ovipositing.

No check plot was used, so no definite idea of the effectiveness of the use of traps as a control measure could be obtained. On May 8, 570 plants were set out and on June 13, 569 were still growing. When a plant wilted, it was at once examined for maggots; in only one case were maggots the cause of the death of a plant. Several plants were retarded by other factors, including cutworms, and there is a possibility that some maggots

were present in numbers too small to kill or wilt the plant. On August 7, 163 plants were so retarded as to be useless. The cabbage maggot was not a serious pest around New Haven this

season.

In experiments elsewhere, allyl isothiocyanate and allyl alcohol have proved attractive to Hylemyia cilicrura and Hylemyia ceparum, and further trials will be made with these materials with the cabbage maggot.

I am indebted to Dr. H. C. Huckett for assistance in determining the species of Anthomyiinae taken in the experiment.

TABLE I.

NUMBER OF FLIES CAUGHT AT MOUNT CARMEL, 1924.

The number of traps is the total gained by considering one trap set one day as one, two traps in one day two, one trap for two days two, etc.