58 



score of the weather. For example, the squash ladybird, Epilachna 

 borealis, which is a thoroughly acclimated species coming originally, 

 though a great many years ago, from the South, was unusually trouble- 

 some in some localities and scarce in others. The same is true of l)ia- 

 brotica vittata, the striped cucumber beetle. 



Of periodically injurious species that were troublesome the present 

 year about Washington, and that do not fall readily into either the 

 Northern or Southern group, are the fall army worm (Laphygma frugi- 

 perda), grass bill- bug (Sphenophorus parvulus), pale-striped flea-beetle 

 (Systena blanda), bean leaf-beetle {Cerotoma trifurcata). and the destruc- 

 tive green pea louse (Nectarophora destructor Johns. MSS.). 



The fall army worm and other cutworms are not apparently very 

 susceptible to changes of the weather. The bill-bugs hibernate in the 

 adult stage, and in this condition are among the most difficult insects 

 to destroy, being long-lived and exceedingly tenacious of life: The 

 plant-lice, though delicate in structure, are really capable of enduring 

 a considerable variation of temperature, and are to be found in activity 

 after severe frosts and long after most insects have sought their win- 

 ter quarters. It is matter of common observation that they are less 

 affected by cold and by the sudden changes which destroy many insects 

 in winter than by heat and dryness, or by dampness or humidity. 

 Prolonged cloudy, wet, or humid weather favors their multiplication, 

 because it is practically only in sunny weather that the parasites of 

 plant-lice are active. The Chrysomelidae, which includes the leaf-beetles 

 and flea-beetles, with but few exceptions, hibernate as adults, and are 

 also unusually vigorous when in this stage, the tobacco flea-beetle 

 being apparently an exception. 



COMPARISONS WITH OBSERVATIONS MADE IN OTHER STATES. 



The observations conducted by the writer in Maryland, Virginia, and 

 the District of Columbia just mentioned, and the deductions drawn 

 therefrom, were independent of those reported by other economic 

 writers, and to bring out this fact more clearly and to show that the 

 conclusions were drawn from personal observation originally, the 

 reports of Messrs. Johnson, Webster, and Quaintance on the same and 

 similar insects, as well as those of Messrs, Marlatt and Scott on the 

 effect of the recent weather on scale insects, are referred to in different 

 paragraphs. The manuscripts from which the notes which follow are 

 taken reached me about the middle of September, after most of my 

 observations had been written down, and as the papers in question 

 have already been published in a previous bulletin of this series (Bui. 

 No. 20, n. s.), where particulars are given, the different species will be 

 only briefly mentioned. 



To begin with, the different species reported by Professor Johnson 

 as injurious during the season in Maryland, the currant worm, Pteronus 

 ribesii, was described as a serious pest throughout the State, and was 



