. Circular. Insects. 4 Unfortunately this parasitic wasp—as with the other beneficial insects—is active only while the temperature is above 56° F., or at least 10° above that at which the " green bug " breeds freely; and. Fig. 5.—Lysiphlebus tritici, pi and antenna of male, greatly nified. (Original.) incipal parasite of the spring grain-aphis : Adult female enlarged. Egg of Lysiphlebus tritici at right, highly mag- green bug herein is the whole secret of the irregular disastrous outbreaks of the iu grain fields. As accounting for the outbreak in the year 1907, the " green bug&q
. Circular. Insects. 4 Unfortunately this parasitic wasp—as with the other beneficial insects—is active only while the temperature is above 56° F., or at least 10° above that at which the " green bug " breeds freely; and. Fig. 5.—Lysiphlebus tritici, pi and antenna of male, greatly nified. (Original.) incipal parasite of the spring grain-aphis : Adult female enlarged. Egg of Lysiphlebus tritici at right, highly mag- green bug herein is the whole secret of the irregular disastrous outbreaks of the iu grain fields. As accounting for the outbreak in the year 1907, the " green bug" had had a whole winter and the following late spring in which to breed and multiply unmolested, and it accomplished its principal damage, as in Texas and southern Oklahoma, before the weather was warm enough for the para- site to increase sufficiently to overcome it. As further illustrative of the important bearing of weather conditions, it is found that in the case of the three important outbreaks of this insect, namely, for the years 1890, 1901, and 1907, the temperature for the first five months of each of these years, including the latter part of winter and spring, was above the normal for the winter months and below the normal for the spring months; in other words, warm winters and cold, late springs. The little parasitic wasp which is so useful in the control of this pest is native to this countn7, widely distributed, and every year does its work with the " green bug and with other aphides. It is always [Cir. 93]. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original United States. Bureau of Entomology. Washington, Govt. print. off.
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Keywords: ., bookcentury1800, bookdecade1890, bookpublishe, booksubjectinsects
