12 BULLETIN 265, U. S. DEPARTMENT OF AGRICULTURE. 



cut off the adult emergence of the second generation to a great extent, 

 and, while a number of males were secured, only a single female 

 emerged. The offspring from this female were successfully carried 

 through, however, to four complete generations, the larvae of the 

 fourth generation, of course, hibernating in their pupal cells and form- 

 ing spring-brood pupae and adults the following year. Additional 

 records were obtained by collecting eggs in the field at the time the 

 second-brood adults were emerging and rearing the larvse from these 

 eggs. It is reasonable to suppose that these eggs were deposited by 

 second-brood adults, since they were collected after July 15, and no 

 spring-brood adults had emerged from the overwintering material 

 after June 16. In selecting adults for oviposition in the insectary, 

 those emerging early and late were, if possible, disregarded, and only 

 those emerging during the period of maximum emergence were used. 

 Since it was not possible to rear a sufficient quantity of the false- 

 worms to get an adequate idea of the time when each generation 

 occurred in maximum numbers, field observations were made from 

 July 1 to September 8, once a week or oftener. This work was done 

 near the field station at Wenatchee, Wash. As many worms as 

 could be found in a couple of hours were observed, and the instar 

 or stage in each case was recorded. From these figures the per- 

 centage of each instar for each date was worked out, thus indicating 

 the broods. Since the infestation was not great enough near We- 

 natchee to afford a large number of worms for examination at each 

 date, the number running from 20 to 100, the detailed figures are 

 not given here. The diagram in figure 4, however, shows graph- 

 ically the percentage of full-grown larvse found on each date. As 

 these figures do not cover the whole season, the lower line is added 

 to the diagram to show the actual number, and not the percentage, 

 of first and second brood larvse passing the final molt each day, 

 from among those reared at the laboratory. It will be seen that 

 where these two lines overlap they correspond fairly well, and the 

 two together show at a glance when the larvse of each generation 

 attain maturity. The curves are shown for the mature larvse, since 

 these are the only ones that ever injure fruit. 



HABITS. 



Since the habits of the individuals of all generations of the dock 

 false-worm are the same, they will not be considered separately. 

 As we have already indicated, the eggs are deposited in the leaf 

 tissue of the food plants (PL I, fig. 1). The larvse, in escaping, eat 

 a small circular hole through the eggshell and the thin epidermis of 

 the leaf, usually the lower, and crawl out. They begin to feed at 

 once, finding a secure foothold on the rough lower surface of the 

 leaf. At first they eat only through to the upper epidermis, leaving 

 this intact as a thin membrane, but after passing the first molt they 

 begin to eat clear through the leaf, forming irregular holes. 



