. Bulletin of the Department of Agriculture. Agriculture. 14 BULLETIN 766, IT. S. DEPARTMENT OF AGRICULTURE. sides were holes covered with fine copper screen, affording good venti- lation. In the center of the front of the tray was a hole 3 inches in diameter, in which was fitted a round plug having a 1-inch hole through the center for inserting a vial containing foliage; by this ar- rangement the stem of the foliage could be kept in water. The experi- ment number label, with the number and species of hosts, number of both sexes of Compsilura, and the date begun, was also pasted on the fr
. Bulletin of the Department of Agriculture. Agriculture. 14 BULLETIN 766, IT. S. DEPARTMENT OF AGRICULTURE. sides were holes covered with fine copper screen, affording good venti- lation. In the center of the front of the tray was a hole 3 inches in diameter, in which was fitted a round plug having a 1-inch hole through the center for inserting a vial containing foliage; by this ar- rangement the stem of the foliage could be kept in water. The experi- ment number label, with the number and species of hosts, number of both sexes of Compsilura, and the date begun, was also pasted on the front. In the right side of the tray was a smaller hole for the purpose of placing the parasites in the tray, this being closed with a cork. During the summer of 1915 sugar water was used as food, being sprayed on the leaves and on the sides of the tray. This was found to be unsatisfactory, first, because sugar water was not heavy enough food for the flies and they did not live for any length of time, and, second, when this sticky substance was sprayed over the leaves and the sides of the tray the flies frequently would become stuck to it. During the season of 191G honey water in the proportion of one part honey to three of water was used very satisfactorily. This was fed to the flies by the use of an atomizer, with which it was sprayed on a sponge placed in a watch glass. In the bottom of the tray was kept a small dish of sand, which was moistened each day, thus keeping the humidity constant. Temperature records were kept with a self-recording thermometer placed near the reproduction trays. The experiments were conducted in a house which had three screened windows on one side and the opposite side built so that about half of it was open and well screened. One end was closed and the other had a screen door in it. The three sides being thus open, good ven- tilation was afforded. The reproduction trays were arranged on two sides of this shed on shelves which were constructed of nar
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