Chas. E. Woodworth.
A Wireworm Double Monster (Limonius canus Lec., Elateridae, Coleoptera).
Psyche 39(1-2):37-40, 1932.

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19321 A Wireworm Double Monster 37
canadensis seems to have fortunately been passed over without being standardized into conformity with the last catalogue.
In the following list of works consulted, the asterisk in- dicates'use of the valid prior name (canadensis Latreille 1810) instead of its synonym (bicolor Newman 1837). *I810 Latreille, Consid. General.-Crust. Arach. Ins. Paris, p. 212, 430.
*I825 Lepeletier & Serville, Encyl. meth., Ins., vol. 10, p. 169, 261.
1837 Newman, Ent. Mag., vol. 5, p. 375.
9853 Melsheimer, Cat. Coleop. U. S., p. 148. *I855 LeConte, Proc. Acad. Nat. Sci. Phila., vol. 7, p. 275. 1859 Lacordaire, Gen. Coleop., vol. 5, p. 603, footnote 3. *I866 LeConte, List Coleop. N. A., p. 64. 1870 Gemmiger & Harold, Cat. Coleop., p. 2104. *I874 Crotch, Check List Coleop. Am. N. of Mex., p. 109. *I885 Henshaw, List Coleop. Am. N. of Mex., p. 129. 1914 Blair, Ann. Mag. Nat. Hist., Ser. 8, vol. 13, p. 313. 1920 Leng, Cat. Coleop. Am. N. of Mex., p. 161. 1928 Blair, Coleop, Cat., Junk, pt. 99, Pyrochroidse, p. 2. *I931 Payne, Ent. News, vol. 42, p. 13-15. A WIREWORM DOUBLE MONSTER (LIMONIUS
CANUS LEG., ELATERIDJE, COLEOPTERA)
BY CHAS. E. WOODWORTH
Associate Entomologist, Division of Truck Crop Insects, U. S. Bureau of Entomology
Quite recently it was my good fortune to find and pre- serve an interesting monstrosity among some newly hatched wireworm larvae. In the course of examining about eighteen thousand of these, only one abnormal in- dividual was noted. Besides the great scarcity of anomalies in this group the fact that wireworms are of subterranean Pu&e 39:37-40 (1932). hup ttpsychu einclub n~M-037.htmS



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38 Psyche [ ~ m h
m. 1. Partial twin, firet instar larval wirewormi ~moiiius canus Lee., ventral aspect, actual length 2 mm. Enlarged 60 diameters,



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19321 A Wireworm Double Monster 39
habits makes observation rare indeed. For these reasons it was decided to report this case. In order to insure that this partial twin should not be lost it was killed and fixed as soon as discovered and, as a consequence, growth records were not obtained. It is hoped that another individual will be found so that developmental changes can be noted. The specific type of anomaly possessed by the individual here reported is classified by Cappe de Baillon2 as a sym- metrical double monster with lateral abdominal doubling. This particular diplopagisity, according to Wilder3, is be- lieved to be due to wide separation of some of the segmen- tation nuclei in early embryonic development, perhaps be- ing traceable to the two-cell stage. Had there been com- plete wide separation there would have been identical twins. In phasmid larvae Cappe de Baillon found that abdominal doubling was very rare as compared to cephalic or thoracic doubling. In fact very few larval irregularities of any type have been reported. In adults abdominal monstrosi- ties are very rare as compared with other types. This fact is strikingly noticed when the literature of reported cases is reviewed.
This particular larva has a perfectly formed head and thorax as well as the first five abdominal segments as far as external study indicates. The sixth segment is irregu- lar in shape, being double at the bottom but single at the top. The last three segments are apparently normal but duplicated. The digestive tract appears to be double throughout the sixth segment and divides at the junction of the fifth and sixth segments, the irregularity beginning about the middle of the fifth. The fat bodies, the only other internal structures visible, seem to conform to the external arrangement. The length of the larva is the same as the rest of the worms from the same mating if either of the tails are used. The volume would be the same if the dup- licated parts were removed and the sixth segment trimmed to normal shape. There does not seem to be any atrophy or hypertrophy except as noted above and each duplicated segment is like the corresponding somite of the other half



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40 Psyche [March
and of other larvae from the same mating except the ab- dominal segment 6.
In 1927 Cappe de Baillon wrote a very excellent book which concerned itself entirely with teratology or mon- strosities found in insects. While the principle part of the work deals with a study of Carausius morosus Brunner, a phasmid, one that is very prone to irregular development, there is included a 382-title bibliography. Practically all of these references refer to adult irregularities, probably because those forms are the ones found in collections. Most of these malformations take place in the pupal reorganiza- tion. How much larger the list would be if larval anomalies such as the one here reported were more often found! In this whole list of references only one deals with elaterids. That one is by Bastine1 and concerns itself with an anten- nal irregularity in an adult of Melanotus rufipes Herbst in which the second antenna1 article had two extra growths upon it.
Bastine, F.
1910 Cas de Monstruosite chez un Elateridse du genre Melanotus Escholtz. Feuille des
Jeun. Nat. 40:147.
Cappe de Baillon, P.
1927 Recherches sur la Teratologie des Insectes. Paris, 291 pages, fig. 85, pi. 9, ref. 382. Wilder, H. W.
1904 Duplicate Twins and Double Monsters. Amer. Jour. Anat. 3: 387-493, fig. 11, pi. 2, ref. 151.




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