42 ASSOCIATION OF ECON'OMIC ENTOMOLOGISTS. 



this insect. Shoukl this infestation become jnore 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 bv 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 Avheu the temperature 

 of a house can be kept down to -10° 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 w^as 

 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 dispfays 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 larva^ from most insect- 

 icides. Furthermore, several of them said that fumigating with 

 hydrocyanic-acid gas apparently has no effect whatsoever in destroy- 

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

 There is a marked periodicity in the apjjcarance of the larva\ Last 

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

 they became abundant again in August. Experience this year has 

 shown tliat they may continue working in numbers 'even as late as 

 the latter part of Octol)er. A number of infested leaves were jilaced 

 on soil on the V2th, at which time no pui)a^ were manifest. The first 

 adults appeared on the 2*2(1 and others emerged subsecfuently to the 

 2r)th, when about four were l)red out. Another individual was ob- 

 tained November ?> and lived to the r)th, at least. Owing to the fact 

 that the phiiits could not be well cared for. it is i)robable 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 

 api)earance of the perfect fly, and it may ])ossibly be a little less. No 

 pupa' wei-e observed on the leaves, and there is no doubt that the 

 insect normal]\ u.udergoes its fiiuil transformations in the soil. 



