Direction Leaflet Number One HOW TO MAKE AND USE SAFE INSECT-KILLING JARS By ALICE GRAY Department of Insects and Spiders The American Museum of Natural History A satisfactory method of killing insects may be something of a problem to the amateur collector, especially since cyanide, the substance most commonly used for this purpose, is just as deadly to human beings as it is to insects. There are liquids, such as ether, that do the job quickly and much more safely, but they are sloppy to use and evaporate so rapidly that the jar must be re-charged many times during a day's collecting. There is, however, a simple method of overcoming these difficulties. First, find a strong glass bottle small enough to fit in your pocket and wide enough at the mouth to admit the largest insect you are likely to catch. If you are interested only in small species, a vestpocket size test tube or little vial would be handy. If you are planning to collect all kinds of insects, make it two jars at least, since butterflies and moths should have one to themselves. Some of the tiny scales with which they are covered come off in the bottle and cling to the other specimens, thus spoiling their appearance, while the weight and the kicking of one big beetle can ruin a dozen butterflies. Each jar should have a tight stopper. A screw cap must fit closely without the usual waxed cardboard lining. The wax might soften in the fumes of the killing fluid and smear the specimens. Some collectors prefer a cork, which can be removed with one hand, especially if it has a loop handle of heavy cord, as shown in the picture. Corks of large size can be obtained from the dealers listed under "cork" in the classified telephone book. Make the cork shallow, about half an inch thick for a half-pint mayonnaise jar. Bore the holes for the cord with a small drill or gimlet, or punch them with an ice-pick or a nail. Force the ends of the cord through the holes with the blunt end of a match-stick, and tie a large knot in each. If the holes are at all too big for the cord, caulk them with soft paper and glue. Secure some plaster-of-paris. A pound will be plenty, and can be bought for a few cents at almost any paint or hardware store. Fill a teacup about 1/3 full of water, less if your bottle is very small. With a spoon, gently scatter the dry plaster on top of the water and let it sink without stirring. When almost all the free water is absorbed and all the plaster is wet, stir carefully until the mixture is smooth. This method of mixing prevents the formation of air bubbles in the plaster. Pour the plaster into the clean bottle until it is about 3/4 of an inch deep, less for a little vial. If the surface is not flat, knock the bottle gently to settle it. Then wait for the plaster to set. If, while you are stirring, the plaster becomes too thick to pour, do not try to soften it by adding more water. Throw it away, wash the container, and start all over again. Never pour left-over plaster down the drain. It may set in the pipes and stop them up. Dump it out onto an old newspaper and put it into the wastebasket. Wash the cup and spoon right away, with plenty of water. The plaster will be very hard to get off when it's dry. Feel the bottle while the plaster is setting. You will find it warm. When it has cooled, but while it is still damp, any plaster which may have splashed onto the sides of the bottle should be removed by scraping with a knife and dusting with a dry cloth. Label the bottle "Insect Killer" so that nobody will throw it out by mistake, and leave it open in a warm place until it is perfectly dry. This will usually take 24 hours, but you can hurry it up, if you have to, by putting the bottle on a hot radiator, or in an oven with the door slightly open. Dry plaster-of-paris is an excellent blotter, and can