61 



In the case of the cucurbits these are of tropical origin, and the insects 

 which affect them are for the most part to be found in the Tropics, from 

 which region they have extended in comparatively recent times north 

 of the Lower Austral life zone. The squash- vine borer will probably 

 not suffer any great diminution, but the pickle worm and the melon 

 caterpillar, being more truly southern and being apparently actually 

 absent from this region at the present time, will doubtless require sev- 

 eral years before they can regain a foothold here, such at least as the 

 former species had in 1897 (See Bulletin No. 19, p. 11). The leaf-footed 

 plant-bug and horned squash bug are somewhat better calculated to 

 survive a cold spell than many species so distinctly Lower Austral as 

 these appear to be. 



The pests of cabbage and other cruciferous crops have been con- 

 trolled more particularly by parasites, although the weather doubtless 

 assisted greatty. If I may be understood as being more specific with- 

 out being subject to the charge of prognosticating, I would say that 

 the harlequin cabbage bug should be on the whole rare next year at 

 the beginning of the season, though it may be fairly abundant in some 

 few limited localities, particularly late in the season and in the absence 

 of an attempt to control it. Even in the case of the last generation, 

 which appears to be the third, this was so small in individuals in 1899 

 that under auy circumstances euough should not survive to work exten- 

 sive injury. Such specimens of the cabbage looper as were collected 

 here and received from the South were mostly parasitized, and this 

 species ought to be held in check by its parasites alone. The imported 

 cabbage butterfly, though numerous early in the season, was apparently 

 almost completely killed off by parasites. As the cabbage Pionea was 

 not once observed all season in 1899 further comment is superfluous. 



Leaving out the insect enemies of cucurbits and cruciferous crops, 

 which have been largely reduced in this region by the cold spell or par- 

 asites, there remain for cucurbits a few species of importance. These 

 include the striped cucumber beetle, common squash bug, melon louse, 

 and squash ladybird. Parasitic and other natural enemies of the first 

 three were noticed to be unusually active throughout the season and 

 their services should have due effect in decreasing the pests for another 

 year, but in spite of these it may happen that any one or all lour will 

 be troublesome, at least locally. 



Of the principal specific cruciferous plant pests which have not been 

 mentioned, the cabbage louse, diamond-back moth, and flea-beetles, 

 were all present during the year, but not in sufficient numbers to jus- 

 tify any fear that any of them will be especially and extensively trou- 

 blesome next season. 



PROBABLE DECREASE IN OTHER INSECTS AFFECTED BY COLD. 



Of other pests mentioned as rare during 1899 on account of the sever- 

 ity of the winter, the tobacco flea-beetle, imbricated snout-beetle, gar- 

 den web worm, and corn stalk borer will probably not again resume 



