42 ASSOCIATION OF ECONOMIC ENTOMOLOGISTS. 



this insect. Should this infestation become more general, the results 

 might be exceedingly serious to the industry as a whole. An exam- 

 ination showed that the insect was distinctly local in its operations, 

 since one-half of a house 150 feet long might be seriously injured, 

 while the other half might be almost free from attack. Even in 

 small houses there were distinct areas which suffered more severely 

 than others, sometimes these being limited to only a square yard or 

 two. The continued breeding of this species appears to be affected 

 largely by temperature, since houses where the mercury was not kept 

 below a certain point were decidedly more infested than others. The 

 growers are almost unanimous in stating that when the temperature 

 of a house can be kept clown to 40° at night and does not rise to over 

 60° in the daytime there is little or no injury from the pest. The 

 flies, according to growers, very rarely leave the plants, and can be 

 observed only by flushing them with the hand. An examination was 

 made in houses where there were flies and numerous larva? on the 

 plants, but none was to be found on the windows nor in the sheds at 

 the ends of the houses, nor in cobwebs spun here and there about the 

 structures. The insect displays a marked preference for recently 

 opened leaves, apparently depositing its eggs in those which have 

 just expanded fully; and, according to the growers, leaves perfectly 

 straight one day may be badly curled the next. They note that 

 leaves can be curled in a few hours, and are of the opinion that only 

 a day or so elapses between the depositing of the egg and the curling 

 of the leaves, an operation which protects the larvae from most insect- 

 icides. Furthermore, several of them said that fumigating Avith 

 hydroc3^anic-acid gas apparently has no effect whatsoever in destroy- 

 ing the larvae, though there is little doubt that the flies are killed. 

 There is a marked periodicity in the appearance of the larvae. Last 

 summer they were first noticed in numbers early in July and then 

 they became abundant again in August. Experience this year has 

 shown that they may continue working in numbers even as late as 

 the latter part of October. A number of infested leaves were placed 

 on soil on the 12th, at which time no pupae were manifest. The first 

 adults appeared on the 22d and others emerged subsequently to the 

 26th, when about four were bred out. Another individual was ob- 

 tained November 3 and lived to the 5th, at least. Chving to the fact 

 that the plants could not be well cared for, it is probable that the 

 period of the appearance of the flies was somewhat abridged by the 

 unnatural conditions. The above data show that not over ten days 

 is necessary from the time the larva forsakes the plant until the 

 appearance of the perfect fly, and it may possibly be a little less. No 

 pupae were observed on the leaves, and there is no doubt that th( 

 insect normally undergoes its final transformations in the soil. 



