June, ’23 
WEIGEL AND DOUCETTE: STRAWBERRY ROOTWORM 
283 
orchard during the past season, and the results here were fairly repre¬ 
sentative of those obtained in the majority of the commercial orchards 
in Central Georgia during the 1922 season. 
President J. G. Sanders: We will now listen to a paper by C. A. 
Weigel and C. F. Doucette. 
CONTROL OF THE STRAWBERRY ROOTWORM 
IN COMMERCIAL ROSEHOUSES 
By C. A. Weigel and C. F. Doucette 
Abstract 
The results of three years’ study of the seasonal and life histories of the straw¬ 
berry rootworm (Paria canella Fab.) under greenhouse conditions, are briefly re¬ 
viewed as a basis in formulating an effective control program. Due to the long 
period of egg-laying the maximum numbers of beetle are present in June and July. 
The second brood emerges during September and October. 
The practice of replacing plants and soil at intervals of several years aids materi¬ 
ally in ridding a house of these insects. Various control measures which have been 
tested in different localities on a commercial scale are discussed. A series of fumi¬ 
gations with hydrocyanic-acid gas during the drying-off period, using 2 ounces of 
sodium cyanid per 1,0G0 cubic feet of space with an exposure lasting 2 hours, killed 
97 per cent of the beetles. (Muslin curtains proved effective in confining the gas 
in separate sections of open-range houses). In one establishment as many as 60,000 
beetles were collected in a week by persistent handpicking. Keeping the foliage 
dusted with a mixture of 10 or 15 pounds of lead arsenate and 90 or 85 pounds of 
superfine sulphur from February to November, protected the plants and killed many 
beetles. Scraping a layer of soil 2 inches deep from the beds after the plants were 
cut-back at the end of the drying-off period removed many beetles. The cut-back 
plants were then sprayed with arsenate of lead at the rate of 4 pounds to 50 gallons of 
water to protect the breaking eyes. Filming the surface of the water, which remains 
on the beds after syringing, with kerosene-nicotine oleate killed many beetles. A 
layer of wood ashes and tobacco dust on the beds operated to some extent against 
the larvae and pupae in the soil. Composting soil for several months or sterilizing 
before it is used in beds aids in keeping a greenhouse free from infestation. 
The attention of entomologists has already been directed to the 
depredations of the strawberry rootworm on greenhouse roses by 
papers which were presented at two previous meetings of this society. 
The first article 1 dealt with the early reports received by the Bureau of 
Entomology regarding its injury to rose and presented the results of 
some preliminary control experiments. The next paper 2 described the 
J C. A. Weigel and E. L. Chambers, Jour. Econ. Ent. April 1920, V. 13, no. 2, 
pp. 226-231. 
2 C. A. Weigel and C. F. Doucette, Jour. Econ. Ent. June 1922, V. 15, no. 3, 
pp. 204-209. 
