THE INSECT WORLD. 



71 



passed on the host, and the insects usually spread from one 

 animal to the other on occasions of contact, or through litter 

 into which some specimens may crawl or be thrown. They also 

 crawl upon the wood-work of coops and stables, and thence upon 

 such animals as may rest against it. 



The only way to reach these insects is by means of poisons 

 acting through the respiratory system, and this is not difficult, 

 because the spiracles are not well protected. Barn-yard fowls 

 will keep themselves tolerably free if furnished with plenty of fine 

 dust. The finer it is the more effective, and the birds will so 

 thoroughly powder themselves that few of the parasites can 

 escape. Cleanliness on the roosts and in hen-houses is impera- 

 tive, and a liberal use of whitewash and occasionally of kerosene 

 on all the wood-work is useful. A badly infected house may be 

 cleaned by shutting it up tight for twenty-four hours, and evap- 

 orating in a shallow dish a few ounces of bisulphide of carbon. 

 This kills all, save eggs, and the treatment should, therefore, be 

 renewed a week later to reach such as may have hatched since 

 that previously made. It has also been recommended to hang 

 small open vials of bisulphide below the perches, and this, it is 

 asserted, kills the parasites without discommoding the fowls. 



On farm animals greasy mixtures may be successfully employed, 

 or carbolic or tobacco washes or dips. For larger animals — 

 horses, cows, or mules — a thorough grooming with comb and 

 brush, dipping the brush into a kerosene emulsion diluted five 

 times so as to moisten all parts of the body, is decidedly the best 

 method. This must be duplicated a week later to reach any that 

 may have hatched from eggs since the previous treatment. On 

 large herds, badly infested, the kerosene emulsion, diluted nine 

 times, is simply sprayed on the animals as they pass through a 

 narrow opening, the application renewed at intervals of a week, 

 until no more lice appear. 



With so considerable a range of remedial and preventive 

 measures no serious trouble from these parasites need be appre- 

 hended, and it remains only to urge again the utmost cleanliness 

 everywhere as the best of all preventive measures. 



All the neuropterous orders heretofore treated have had the 

 metamorphosis incomplete, and are therefore classed as pseudo- 



