182 Annals Entomological Society of America [Vol. IV, 



setts Society for Promoting Agriculture. The essay was 

 printed by the Society but it has now become very scarce. 

 Harris, writing in 1841, said that the pamphlet was then "out 

 of print and rarely to be met with." It was the good fortune 

 of the writer to find this paper of fourteen pages in the Boston 

 Public Library last winter. That so much concerning the habits 

 of this insect had been determined at such an early date in the 

 history of American economic entomology, is indeed surprising. 

 In fact, almost all of the information concerning the insect 

 in America dates back to the account of Peck. 



The insect is widely distributed, having been recorded in 

 Europe, North America, Australia, New Zealand and South 

 Africa. 



LIFE HISTORY. 



Generations. There are in central Iowa two quite distinct 

 generations of the insect. In the fall a very few slugs were 

 found, lagging way behind the others, but these are probably 

 only delayed individuals from the second generation, rather than 

 a partial third generation. 



About Ames the eggs and adults were found in late May and 

 early June and larvae appeared in the fore part of June. By 

 July 5 the first brood slugs were practically all gone. The 

 adults from this brood of slugs appear about the middle of July 

 and their eggs hatch late in the month. The slugs begin to 

 mature a little before the middle of August and by September 

 1st they are practically all gone. 



A part of the first brood larvae do not complete their trans- 

 formations at once after entering the soil but remain as larvae 

 until the next spring, making but one generation a year for a 

 part of the slugs. This was noticed by Professor Peck and later 

 by Marlatt. It seems to be a provision for the preservation of 

 the species. Should the second generation be wiped out by 

 natural enemies, the slugs that are held over would still be left 

 to propagate the species the next season. 



The Egg. The eggs are deposited in the leaf tissue of the 

 various food plants — placed just beneath the upper epidermis 

 and thrust through the leaf from below. 



In the insectary eggs hatched in 10 to 14 days in the spring; 

 average, 12.1 days; in summer in 7 to 13 days, average, 10.5 

 days. 



