THERMAL CONSTANT FOR LOCUST-EGGS. 427 



temperature of 120° made the 'hoppers lively and happy, but at 140° they quickly 

 died. 



Mr. B. Yates, in the Saint Paul Pioneer-Press, says that 'hoppers hatched out by 

 stoves, when grown to one-fourth inch long, endured 15° and 18° below zero without 

 injury. 



Last winter, -^hen the thermometer marked 24° below zero, I examined eggs in a 

 piece of ground that had been bare all winter, and found them apparently as free 

 from frost as so much alcohol, and in the spring they hatched out in great numbers in 

 the same ground. — [W. J. Newell, Athol, Sioux County, Iowa, July 2, 1877. 



Eggs laid in September, 1876, began to hatch about April 10th. Very cold weather 

 April 24 to 29. Many eggs began to hatch rapidly on May 1st. Insects exposed in a 

 bottle to 14, were not injured. — [G. V. Swearingen, Sidney, Iowa, May 1, 1877. 



On the 27th May, 1877, at Montevideo, Chippewa County, I found a place where the 

 hatching had begun in the early part of the month and had been suddenly arrested by 

 rain; the egg-pods were found to be spreading, the young having been arrested jast 

 as they were in the act of breaking the shell. The eggs appeared to be lifeless, but 

 after lying in the warm sun a few minutes a portion of the young came forth. » * * * 

 Eggs plowed under in the spring in corn-fields remained unhatched until June 21, and 

 were then apparently lifeless, but hatched under the sun within an hour. Where the 

 ground has become baked hard by the sun, a light raia-shower, followed by warm sun- 

 light, often serves to assist rather than to hinder hatching. — [Mr. Allen Whitman, 

 Saint Paul, Minn. 



Eggs deposited July, 1875, and covered by water through the spring and summer to 

 August first, were hatching out on August 28 in the warm sun. Alternate freezing and 

 thawing occur every year ; thus March, 1874, had sixteen days of temperature above 

 32°, and it fell, April 3, to 17o. In March, 1875, ranged from 38° to 1°, and in April, 

 1875, the range was from 57° to 10°. In March, 1877, above freezing-point, and on 

 eighteen days in April. — [C. H. Goodsell, Marshfield, Lincoln County, Minn. 



NotwithstancliDg the indefioite nature of some of tlie preceding 

 observations, we have ventured to draw the following conclusions in 

 reference to the influence of temperature, &c., on the vitality and hatch- 

 ing of the eggs : 



I. Low degrees of cold, as — 5° F. and — 24 F., do not impair their vitality. 



II. Temperatures up to 100° F. do not destroy them. 



III. Moisture and water affect the eggs principally by keeping them at a low tem- 

 perature and delaying the time of hatching; by drying uj) the contents of the egg, 

 by exposure to sun and wind, its development may be prevented at any temperature. 



IV. Alternate freezing and thawing injures the eggs but slightly if the process is 

 slow, but if the thawing takes place very rapidly the vitality is probably injured. 



V. The development of the egg is suspended for an indefinitely long time when kept 

 at temperatures uniformly lower than 32° F., and even probably lower than 50°, but 

 progresses at higher temperatures with a rapidity proportional to the excess of the 

 temperature above 50°. 



VI. Some of the preceding experiments give the following numerical data for the 

 time of hatching : 



Eggs that had perhaps been already brought forward by natural heat out cf 

 doors, hatched after 20 days' exposure indoors to an artificial temperature ranging from 

 55° at night to 65° by day, and averaging 60°. Other eggs, perhaps those that had 

 not as yet made so much progress in maturing, required 38 days at the same tempera- 

 ture. — [Riley's Experiments, 1. 



Eggs hatched in from 21 days, at 60° F., to 32 days, at 6€o F.— [Riley's Experi- 

 ments, 2. 



Eggs hatched in from 21 days, at 60° F., to 36 days, at 60° F. These eggs were 

 exposed from December 22 to January 12 to out-of-doors temperatures ranging from 



