Lightning not dangerous to aircraft in flight

• Book ID: 104129732
• Publisher: Elsevier Science
• Year: 1934
• Tongue: English
• Weight: 77 KB
• Volume: 218
• Category: Article
• ISSN: 0016-0032
• DOI: 10.1016/s0016-0032(34)91381-8

✦ Synopsis

The U. S. Department of Agriculture points out that most of the liquid household insecticides now on the market contain insect poisons known as the pyrethrins, which have been obtained from pyrethrum flowers and put into solution in kerosene.

Kerosene itself has some action on house flies, but the major effect is produced by the pyrethrins in it. Flies that come in contact with mist from a phrethrum-kerosene spray immediately "nose-dive" to the floor. They appear to be dead, but really are only paralyzed.

Some of the paralyzed flies die, but others recover later and become as capable of annoyance as they were before.

The Department is vitally interested in not only how to knock flies down but to keep them down.

It was natural that the effect of derris also be determined.

Derris, a woody vine related to our locust tree, grows wild and is also cultivated in the East Indies.

The immediate effect of derris was not so spectacular as that of pyrethrum. The flies remained in the air longer and offered more resistance to "taking the count," but once they were down they remained down and in the end derris killed a larger percentage of the sprayed flies than did pyrethrum.

An insecticidal spray containing both derris and pyrethrum should exert the "knock-down " effect of the latter and the "drag-out" of the former.

C.