588 ANNUAL REPORT OF THE Off. Doc. 



Diu-ing late July, August, and early September there is fre- 

 quently a heavy deposition of eggs oi" the second brood. It is the 

 larvae from the second brood eggs that aie mainly responsible for 

 injury to grapes just previous to the ripening period. In some in- 

 stances where the infestation is very heavy the crop may be almost 

 a total loss. Most ot the larvae escape from the berries before the 

 fiuit is picked. Instead of making their cocoons on the leaves at- 

 tached to the vines they drop to the ground and make them upon 

 the few leaves that have fallen prematurely and have been held be- 

 neath the trellis either by sticking to the moist earth or by being 

 held by weeds. Sometimes a dozen to thiriy pupa cases may be 

 found upon a single leaf plastered to the damp soil. In these leaves 

 the insects pass the winter and from the over-wintering cocoons the 

 moth emerges in the spring and deposits eggs on the blossom clusters 

 and berries as described. 



This insect has proved to be one of the most diificult pests of 

 the grape to control. In field experiments conducted at North East, 

 Pa., the most effective treatment has been the heavy application of 

 a spraj^ consisting of three jjounds of arsenate of lead to 50 gallons 

 of water driven forcibly into the grape clusters just previous to and 

 again a few days after the grapes have blossomed. It is very neces- 

 sary to curtail the development of larvae of the first brood since, 

 later in the season as the berries increase in size the clusters be- 

 come compact and the spray cannot be driven between the indi- 

 vidual berries. In addition to this objection to poison applications 

 for the second brood larvae, the poison leaves the ripened fruit die- 

 colored and in an undesirable condition for table use. Hand pick- 

 ing berries infested by the first brood larvae where limited areas are 

 attacked win greatly lessen the number of the second brood. Since 

 it has been ascertained that practically all of the overwintering in- 

 sects pupate on a small percentage of leaves which have dropped 

 prematurely beneath the vines, it has been suggested that an attempt 

 be made to destroy these leaves, either by gathering them before the 

 rest of the leaves have fallen from the vines, or by covering them 

 with soil by turning a couple of furrows under the trellis before 

 the remainder of the leaves have dropped. 



The Grape-Blossom-Bud-Gnat, Contaria johnsoni, is an insect in- 

 festing the blossoms of grapes which has atti acted more or less 

 attention during the past few years in the vineyards of Erie county. 

 Although quite generally scattered through the vineyards of the east- 

 ern portioir of the township of North East, Pa., no instances have 

 come under our observations where it has greatly lessened the crop 

 yield. In Chautauqua county, N. Y., in one instance it has been 

 very destructive to the crop on a snrall block of Moore's Early vines 

 for several seasons. 



During the past season it was very destructive on a number of 

 small Concord vineyards in the vincinity of Sandusky, Ohio. 



The adult insect is a small gnat which deposits its eggs in the 

 blossom bud of the grape. The larvae, of which they may be from 

 a dozen to fifty in a single bud, get their full devclo])ment before the 

 grape blossoms unfold. Infested buds are readily recognized since 

 they are much larger than the normal buds making a more fleshy 

 growth, and taking on a yellow or reddish color. The niaggots 

 working inside the blossom bud injure the ovary, thus preventing 



