when diluted not more than 1 part to 10 parts of water. Against eggs, in two tests each, a 3, 5, and 10 per cent solution of crude carbolic acid appeared to prevent hatching. SOAP. Effect on carpet-beetle larvæ and eggs.-Fish-oil soap, used at the rate of 1 pound to 4 and 8 gallons of water, killed 100 per cent of the larvæ. When used at the rates of 1 pound to 10, 16, and 25 gallons, from 75 to 90 per cent were killed, while weaker solutions proved ineffective. Practically the same results were obtained by the use of laundry soap. Laundry soap, used at the rate of 1 pound to 10 gallons of water, appeared to kill all carpet-beetle eggs in two tests. When used at the rates of 1 pound to 20 and 40 gallons of water it was not effective against the eggs. NICOTINE SOLUTIONS AND TOBACCO POWDERS. Effect on carpet-beetle larvæ.-Table VIII shows the results of tests with nicotine in various forms against the carpet-beetle larvæ. TABLE VIII.-Tests of the killing effect of nicotine solutions and tobacco powders upon carpet-beetle larvæ. As will be noted, it was necessary to use a tobacco extract (40 per cent nicotine, as sulphate) diluted at the rate of 1 part to 10 parts of water to kill all the larvæ. All weaker dilutions used failed to kill more than 75 per cent. It is therefore apparent that nicotine sprays. are not to be recommended for carpet-beetle larvæ. Powdered tobacco, containing 4.56 per cent of nicotine, which is considerably above the average percentage of nicotine content for such powders, was ineffective against the larvae when used as a dust. In addition to the foregoing tests tobacco powder containing 0.85 per cent nicotine was burned in a box at the rate of 6 ounces to 360 cubic feet. None of the 15 larvæ used in this box fumigation were killed in 19 hours. The strength was increased to 26 ounces to 360 cubic feet with the result that 20 per cent of the larvæ were killed. Effect on eggs.-A solution containing 40 per cent nicotine extract, used at dilutions of 1 part mixture to 25 and 1 to 50, killed nearly all the eggs, while dilutions of 1 to 75 and 1 to 100 were not effective. It appears from these tests that the various forms of nicotine are of no practical value against carpet beetles. MISCELLANEOUS SUBSTANCES. Effect on carpet-beetle adults.-Oil of cedar leaves effectively protected flannel from carpet-beetle infestation in laboratory-cage tests. Lavender flowers were ineffective in such tests. Formaldehyde fumigation (2 ounces to 360 cubic feet) proved ineffective against adults. Effect on larva.-Miscellaneous substances tested against carpetbeetle larvæ and found to be more or less effective are as follows: Alcohol (ethyl), 50-95 per cent solutions. Cloves (powdered). Gasoline (undiluted). Mercuric chlorid (1 pound to 50 gallons of water). Sulphur (burned), 8 ounces to 360 cubic feet. Miscellaneous substances found to be ineffective against larvæ are as follows: Effect on eggs.-Solutions of ethyl alcohol at 30, 50, 70, and 100 per cent appeared to prevent the hatching of carpet-beetle eggs. A 20 per cent solution, however, was of no value. Borax, gasoline, mercuric chlorid (1 pound to 50 gallons of water), and sulphur failed to prevent hatching of eggs. HEAT. Effect on carpet-beetle larva.-Tests of the effect of heat were conducted by placing 10 larvæ on flannel in an incubator for varying lengths of time. The results are shown in Table IX. Effect on eggs. Ten or more eggs on a piece of flannel were placed in an incubator for varying lengths of time. The results are shown in Table X. TABLE X.-Effect of heat on carpet-beetle eggs. To kill all larvæ, a temperature of 120° F. maintained for 30 minutes was required. Higher temperatures for less time were equally efficient. To prevent all eggs from hatching, it would appear, from these limited tests, that the length of exposure is more important than the temperature. A temperature of 125° F. for 16 minutes killed the eggs, while an exposure of 128° F. for 11 minutes failed to kill all the eggs. Two pieces of flannel, each containing 10 or more eggs, were placed in the hot sun for three hours. The temperature on the flannel ranged from 109° F. to 120° F. Observations showed that none of the eggs so exposed hatched, while practically all the eggs on the unexposed flannel hatched. HOT WATER. Effect on carpet-beetle larvæ and eggs.-Flannel dipped for five seconds in water at a temperature of 140° F. resulted in the killing of both larvæ and eggs, while water at a temperature of 122° F. failed to kill either larvæ or eggs. SUMMARY. 1. Naphthalene, against carpet beetles, as against clothes moths, proved effective in preventing infestation of clothing and in killing all stages of the insect. 2. Camphor was effective against the various stages of the carpet. beetle, but killed much more slowly than did naphthalene. 3. A red-cedar chest killed adults and newly hatched larvæ, but had no effect on larvæ half grown or larger. 4. Red-cedar chips proved only moderately effective against carpet beetles. 5. Pyrethrum powder proved considerably less effective against carpet-beetle larvæ than it did against clothes-moth larvæ. 6. Various mixtures of mineral oils killed carpet-beetle larvæ, when used undiluted or but slightly diluted. 7. Laundry soap killed both larvæ and eggs when used in strong solutions. 8. Nicotine solutions and tobacco powders proved of no practical value against this insect. 9. Oil of cedar leaves was effective, and lavender flowers ineffective, in protecting flannel from carpet-beetle infestation. 10. Ethyl alcohol (50-95 per cent solutions), powdered cloves, gasoline, mecuric chlorid, and fumigation with sulphur (8 ounces to 360 cubic feet) killed the larvæ effectively. 11. Ethyl alcohol (20 to 40 per cent solutions), allspice, arsenious acid, borax, formaldehyde fumigation, hellebore, lavender flowers, lime, black pepper, sodium fluorid, and sulphur were ineffective against the larvæ. 12. Ethyl alcohol (30, 50, 70, and 100 per cent solutions) killed carpet-beetle eggs, while borax, gasoline, mercuric chlorid, and sulphur failed to kill the eggs. 13. Heat killed the larvæ, when exposed in an incubator for 30 minutes at 120° F. A higher temperature was required to kill the eggs. 14. Hot water killed both larvæ and eggs, when the infested flannel was dipped for five seconds at a temperature of 140° F. ADDITIONAL COPIES OF THIS PUBLICATION MAY BE PROCURED FROM 5 CENTS PER COPY By C. H. KYLE, Assistant Physiologist, Office of Corn Investigations. Most corn growers fail to realize that by improving the shuck covering on their corn by selection they may reduce the amount of damage done to the grain. Growers generally consider nothing but the ears and kernels when selecting seed. In weevil-infested sections in particular, variation in the damage of ears is frequently observed, but if the matter is considered the cause is usually attributed to variation in the hardness of the grain. Weevils attack corn of all degrees of hardness, and their progress in consuming the hard corn is only slower than that in the soft corn. Some observers have concluded that since weevils are able to eat the hardest corn, they would also cut their way through the most resistant shucks in order to feed upon the grain, if sufficiently urged by hunger. Others have observed that earworms may cut holes through a large percentage of the protecting shucks and that weevils will enter through these holes, and they have concluded from this that shuck covering can not be made a practicable means of protection. Then, too, there is a sentiment on the part of some against a large amount of shuck.\ With such a formidable array of misconceptions and real difficulties as these and others, it is not surprising that little or no action 59563-18-Bull. 708 |