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78 > Image 78 of Annual report. 1921

Part of Kentucky Agricultural Experiment Station

. 1 / l { ` i t 20 Bulletin N 0. 231 the trees when these were cut open. No pupae or adults were, however, found in the burrows, and but few young grubs of V the size generally to be taken from trees at this season of the . year. Nor has a careful search of walnut trees* in the vicin . ity revealed other adults. There are no hickory in the im- A mediate vicinity. pl For some time the author has been disposed to accept the T t views of B. D. Walsli and Dr. Horn as to the distinctness of the spring and fall forms known under the names Oyllcne rob- 2 iniac and C. picta, tho he formerly had doubts as to the re- l liability of the characters used by them. The facts given above ( suggest several alternatives as possible explanations of the re- lations of the spring form with those so common on goldenrod and locust trees in the fall: ' (1) Either there are two distinct species, as has long been ` assumed, one living on hickory and walnut and appearing in the spring of the year as adults, the other living on locust and ap- Q pearing as an adult in the fall. . (2) Or, there are two forms of one species, one form ap- ` - _ pearing in spring as adults on locust, hickory and walnut, the other appearing only on locust in the fall. (3) Or, there are two forms of the Locust Borer, one . maturing in the fall, the other in the spring, the latter brood ~ diifering in no essential feature from the species appearing as Y adults on hickory in spring. V E At present the writer is disposed to accept the second of these hypotheses, and to hold that a spring brood, the males Y with stronger, longer antennae and both sexes with a tendency i _ to grayness in the markings, appears on several different trees, . ` the locust among them, while a second form of the same species ( appears in fall only on the locust. The facts here given at Q least reopen the question as to the distinctness of the borers, and add a fact of some economic importance to our knowledge of . the habits and life-histories of these insects. , of the early writers on the Hickory Borcr claimed that it at- Y tacks black walnut, and l`itcl1 (Fifth Ann. Heir ii. Sl) assertcrl that this . tree produces larger beetles with gray instead of yellow bands,