44 DECIDUOUS FRUIT INSECTS AND INSECTICIDES. 



have been made by the various authors. For northern hititudes we 

 are unable at present to form any definite conception as to the number 

 of generations. 



LENGTH OF THE IJFE ( YCLE. 



The length of the Ufe cycle or developmental period of a genera- 

 tion of the lesser peach borer, based on field observations, has already 

 been given in connection with Table II. The life cycle of the summer 

 generation was approximately 4^ months, and of the winter genera- 

 tion 7^ months. Fortunately Mr. Quaintance has succeeded in actu- 

 ally rearing a single specimen of this insect through its entire cycle, 

 in the grounds of the Insectary of this Bureau. On September 5, 

 1905, he placed 8 recently hatched larva^ in small artificial wounds 

 made 3 feet from the ground on the trunk of a peach tree. Each 

 larva was placed in a separate wound and the whole then protected 

 by a wrapping of paper. By October 1, not quite a month later, 5 

 of the larvae were found in their respective w^ounds and had grown 

 remarkably, being from a half to five-eighths of an inch in length 

 (13 to 16 mm.). On the 24th of the same month, or just over a 

 month and a half after hatching, the fiA^e larva' were still alive and 

 were either about to molt or had just done so; three of them measured 

 13 mm,, one 10 nun., and the fifth, 19 nun., averaging about 15 mm. 

 The, following spring, on April 5, 190(), another examination was 

 made, and it w^as found that 4 of the larvae had j)erished. The re- 

 maining one was inactive, but began to feed voraciously five days 

 later, and by about April 13 had formed its cocoon and pupated. 

 The moth, a male, emerged on May 14, 190(5. 



The lengths of the respective stages for this individual were as fol- 

 lows: Egg, 7^ days; combined larval instars, 220 days; pupal instar, 

 31 days; making a total of 258 days, or 8.() months for the cycle 

 (from August 28, 1905, to May 14, 190()). This agrees remarkably 

 well with time approximated for the winter generation in the South, 

 Avhere the periods of larval inactivity during the cold months are 

 naturally shorter, and hence growth is more rapid. The individual 

 reared was a descendant of parents from Fort Valley, Ga., mailed to 

 Washington. 



NATURAL ENEMIES. 



The lesser peach borer has a number of natural enemies, nearly all 

 of Avhich are parasites belonging to the order Hymenoptera. 



Elachertut< n. sp., of the fandly Eulophidse, as determined by Mr. 

 E. S. G. Titus, is probably the most connnon, and is an internal para- 

 site which is fatal (o the host just befoiv pupation. After the host 

 larva has constructed its cocoon the parasitic grubs eat their way 

 through its body and pupate nakedly in the host cocoon, entirely 

 filling it. As many as 138 of these parasites have been reared from 



