254 INSECTS AFFECTING VEGETATION 



becomes advisable to destroy all trash in and around tobacco fields 

 and tobacco barns. Pick infested leaves every fourth day. 



The Tobacco Thrips. It was first reported injurious to tobacco 

 in Florida in 1902. It sucks the leaves along the veins, producing a 

 whitened inelastic vein w ? hich breaks too easily for use as a wrapper. 

 Mr. Hooker states that the life cycle requires only twelve to thir- 

 teen days in May and June and that the insect probably hibernates 

 as an adult. Preliminary experiments have led the writer to suspect 

 that the adult has a subterranean habit of hibernation. It feeds 

 upon many species of plants. He found that kerosene emulsion was 

 the cheapest and most efficient remedy. He recommends the fol- 

 lowing stock solution: Kerosene, 2 gallons; hard soap, % pound; 

 water, 1 gallon. A strength of 1 part stock solution to 10 parts 

 of water proved to be effective in killing the thrips, but it was found 

 to injure tobacco seriously if applied in strong sunlight. Spraying 

 is done, therefore, late in the afternoon and at night, beginning not 

 earlier than 5 o'clock on bright days. 



The Tobacco Crambus. The tobacco crambus was recorded 

 from tobacco by the late Prof. W. G. Johnson in 1899. Johnson 

 stated that it was very injurious to Maryland, boring and feeding 

 upon the stems of the newly set plants. 



The Cigarette Beetle. Severe loss to the tobacco trade is caused 

 every year by the cigarette beetle. It breeds in practically all cured 

 tobaccos, except those richest in nicotine. Small lots of infested to- 

 bacco, like cigars, cigarettes, and boxes of pipe tobacco, may be suc- 

 cessfully treated by opening the boxes so that the gas will enter, plac- 

 ing them in an air-tight box, and fumigating with carbon bisulphid, 

 using 1 ounce of the liquid to every 50 or 60 cubic feet of space. 

 The liquid should be placed in a shallow receptacle above the tobacco, 

 for the gas is heavier than air. Large buildings or rooms may be 

 fumigated. with this gas. In these cases securely chink all cracks, 

 place the liquid in pans near the ceiling, and fumigate for from 12 

 to 24 hours, using 1 pound of carbon bisulphid to 600 or 800 cubic 

 feet. 



Do not bring fire into the room while the liquid is evaporating, 

 for the gas is very inflammable. Air the room before entering. A 

 small amount of the gas may be inhaled without ill effects, but a 

 slight dizziness or nausea is the signal for retreat. Hydrocyanic- 

 acid gas has been used to fumigate factories with good results. Great 

 caution being exercised in using it, as it is highly poisonous. No 

 satisfactory method of treatment has been found for this beetle in 

 baled tobaccos. This question is a serious one with cigar manufac- 

 turers and demands investigation. 



The most serious insect of secondary importance that attacks 

 the seed bed is the grouse locust, which, as reported by Mr. Metcalf, 

 was found seriously injuring plant beds at Stem, N. C. This species 

 has also been found rather common upon seed beds at Clarksville, 

 Tenn. Mr. Metcalf advises that plant beds should not be placed near 

 low, marshy ground. As a remedy he advises the spraying of a strip 

 3 feet wide around the plant bed with kerosene emulsion. The kero- 



