9 
The caterpillars form cylindrical silken tubes in which they feed, and 
it is in great part their habit of web spinning that renders them so 
injurious where they obtain a foothold. Upon attaining full growth 
the caterpillar leaves its original silken domicile and forms a new web, 
which becomes a cocoon, in which to undergo its transformations to 
pupa and toimago. It is while searching for a proper place for trans. 
formation that the insect is most troublesome. The infested flour 
becomes felted together and lumpy, the machinery becomes clogged, 
necessitating frequent and prolonged stoppage, and resulting in a short 
time in the loss of thousands of dollars, in large establishments. 
Although the larva prefers flour or meal, it will attack grain when 
the former are not available, and it flourishes also on bran, prepared 
cereal foods, including buckwheat grits and crackers. In California it 
lives in the nests of a wild bumble-bee and in the hives of the honey bee. 
In Europe it has been observed that the insect is able to complete its 
life cycle in two months, but from experiments recently conducted at 
Washington it has been demonstrated that under the most favorable 
conditions—i. e., in the warmest weather—the life cycle may be passed 
in thirty-eight days. In its outdoor life there are probably not more 
than two or three broods in the year, but in well-heated mills or other 
buildings six or more generations may be produced. 
This insect is rapidly becoming distributed throughout the civilized 
world, but as yet its range is limited. From the reports of its alarming 
destructiveness in Great Britain and Canada, it would readily be 
inferred that this moth is peculiarly qualified for an indoor existence 
in much colder climates than most other grain insects. 
When a mill is found to be infested, the entire building should be 
fumigated, and in case a whole district becomes overrun the greatest 
care must be observed not to spread the infestation. Uninfested mills 
should be tightly closed at night, and every bushel of grain, every bag 
or sack brought into the mill, subjected to a quarantine process, by 
being disinfected either by heat or bisulphide of carbon. 
THE INDIAN-MEAL MOTH (Plodia interpunctella Hbn.). 
An insect known as the Indian-meal moth may often be seen flying 
about in mills and stores, where it feeds on edibles of almost every 
kind—meal, flour, bran, grain of all sorts, dried fruits, seeds and nuts, 
condiments, roots, and herbs. 
The adult moth is shown in the accompanying illustration (fig. 6, @). 
It measures across the expanded wings between a half and three- 
fourths of anineh. The inner third of the fore-wings is dirty whitish 
gray, and the outer two-thirds are reddish brown, with a dull coppery 
luster. The caterpillar is shown at ¢, e, d, and f and the chrysalis at b. 
The caterpillars spin large quantities of silken threads with which 
they fasten together seeds, grain, or particles of whatever material they 
happen to infest, and it has recently been observed that they have a 
