THE STATE ENTOMOLOGIST. • J 



1, Fig. 48), which is the only genuine parasite yet known to attack it; and 

 what with the work of such natural enemies and the efforts of man, the pest 

 suddenly became about as scarce as it had been numerous before. 



All accounts agree as to the sudden diminution of its numbers in the 

 month of June, and so far as Missouri is concerned, it did not increase to any 

 alarming extent during the rest of the year. The disappearance was, in 

 many sections, so thorough that it is very questionable whether man and natur- 

 al enemies should alone be credited with the cause. The spring was uncom- 

 monly dry and warm, and, so far, was favorable to the increase of the in- 

 sect; but the summer drought and extreme heat which followed were quite 

 unfavorable to its multiplication. Warm, dry weather in spring is conge- 

 nial to the growth and well-being of the larvae as they swarm upon and de- 

 vour our vines; but at a later stage of their lives when they have to enter 

 the earth to undergo their transformations, a great many of them will un- 

 doubtedly die if the earth continues excessively dry and hot. They will, in 

 short, be dried and baked to death. Those who have had large experience 

 in breeding insects, and who understand the importance of coolness, and es- 

 pecially of moisture in the successful development of those which transform 

 underground, feel perfectly warranted in such an inference, even though no 

 systematic and accurate experiments have been made to test its validity. 

 The extreme heat and dryness of the season, furnished a good opportunity 

 to employ the sun-scalding remedy, and it was fully shown that in an in- 

 tense summer sun, the larvae and even the beetles will very generally die if 

 knocked from the vines on to the dry and heated ground, especially if the 

 vines have been well hilled ; and it is doubtless because the insect cannot 

 thrive when the thermometer ranges near 100° F. that the southern 

 columns of the spreading army extend far more slowly than the northern. 

 Moreover, the past summer was not the first one in which the sudden dis- 

 appearance of this insect under conditions of heat and drought has been no- 

 ticed; for a similar state of things occurred in 1868, and Dr. Henry Shimer, 

 of Mt. Carroll, 111., then attributed such disappearance to the dryness of the 

 season.* 



We are justifiable, therefore, in concluding that while dryness and warmth 

 may be verj^ pleasant and agreeable to the Colorado Potato Beetle in the 

 spring or in the fall, they are nevertheless very destructive to it when inten- 

 sified in the summer months. 



Amount of Damage caused by it in Missouri. — l^otwithstanding such 

 sudden disappearance of the potato bug, the falling off in the potato pro- 

 duct of the State compared with 1870 is fully 20 per cent. In Illinois it is 

 35 and in Michigan 34 per cent.; while in most of the so-called Middle States 

 it has increased. Much of this decrease may justly be attributed to the same 

 heat and drought that killed off the bugs, but a certain amount of it may be 

 attributed to the early ravages of the latter. In 1870, the Statistician, Mr. 

 J. E. Dodge, informed me that the potato crop of Missouri was 5,525,000 

 bushels; and after careful estimates of the average market price in St. 



• Am. Naturalist, Vol. III. pp. 91-99. 



