Francis X. Williams.
Notes on the Life-History of Methoca Stygia Say.
Psyche 23(4):121-125, 1916.

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19161 Williams~Life-Histmy of Methoca stygia Say 121 NOTES ON THE LIFE-HISTORY OF METHOCA STYGIA SAY.
BY FRANCIS X. WILLIAMS,
Melrose Highlands, Mass.
The Thynnidix, a family of aculeate wasps seems to find its metropolis in Australia.
There, many large and striking forms
occur-in strong contrast to our own modest species and to those of Northern Europe, represented indeed by the single genus Methoca. The diversity between the two sexes of the same species, in our forms at least, is so great-the male comparatively large, with coarse sculpture, compact thorax and well developed wings- the female small, slender and ant-like, that one does not wonder that they were first placed in separate genera, namely Tengyra and Methoca.
The Thynnidix have several points in common with their gen- erally hirsute relatives, the Mutillidse, as for example, the apterous condition and ant-like appearance of the female, her long curved sting, hardness of body, and the habit of the male of carrying his mate about in his mandibles, a procedure possible in the Mutillidse however only where the male is much larger than the female and capable therefore of flying about with her. I was prompted by the researches of Adlerz ('03, '05) and of the Champions ('14, '15), on the biology of Methoca ichneumonides Latr. of Britain, Belgium, Scandinavia, and other parts of Europe to make observations on our own New England species, Methoca stygia Say, and while meeting with indifferent success, I was able to note that the habits of the two species are very similar. Like its European cogener the female varies greatly in size, the series in my collection has its smallest individual 3.75 and its largest 7 mm. long, while the Champions have found M. ichneu- monides to vary from 4 to 9 mm. The male of M. stygia, Fig. 1, is about 11 mm. long and shining black, with the head and thorax coarsely punctate, and the clypeus with a prominent median tooth. The abdomen is polished and rather coarsely punctate, with the segments, particularly 1 and 2, strongly separated by well-marked constrictions, which are deepest ventrally. The end of the ab- domen is armed with an upcurved ventral spine over which is a



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122 Psyche- [August
hairy tubercle-like process. The insect is rather sparsely pubes- cent. The female, Figs. 3 and 5, averages about 5 mm. long and is polished and only slightly and delicately punctate. The head is blackish, or at least darker in color than the reddish to brown- ish black body. The thorax is long and slender and constricted into three subequal portions. The abdomen is petiolate and conic- fusiform. The legs are long and the insect nearly devoid of pubescence. Sharp states that this sex might well be taken for an ant, and this certainly hold true for our own species, which in the field superficially resembles a Formica, and to my mind ap- proaches F. schaujfusi more than any other species in the neigh- borhood. But Methoca possesses curved and not elbowed antennae, and her conically pointed abdomen has a rapid and distinctive up and down movement. Locomotion is swift and more or less jerky and zigzag.
Prior to 1903 nothing appears to have been published concerning the biology of the genus. In July, 1903, Adlerz observed a female M. ichneumonides literally place itself in the open mouth of a Cicindela larva, which seizing her, was instantly paralyzed by a sting in the neck from the active wasp. Subsequently Adlerz witnessed this procedure many times by placing Methocas with Cicindelid larvae in a large glass vessel containing hard-packed soil in which the larvae had excavated their trap burrows. The activi- ties of Methoca in this connection were somewhat as follows: When the tiger-beetle larva had closed the entrance to its bur- row by means of its horizontally placed head and thorax, Methoca was seen to run around the insect and at a suitable moment place herself on this animated lid. Instantly Cicindela raised its head to seize the wasp in its forminable, sickle-shaped jaws, but the upward movement of the head exposed its soft neck to the im- mediate and paralyzing sting of Methoca. When her venom has taken full effect she slides down into the burrow, indulges in further stinging and malaxation, drags her prey further down, fastens her long white egg behind one of the posterior coxae and completes her work by filling up the hole and carefully disguising its location. If the Cicindela larva is not at the top of the hole Methoca plunges boldly in and does not reappear until she fills up the burr0w.l 1 It may be remarked here that the large spider wasp, Pepsis formosa of the west does not always vanquish the hairy tarantula when the latter is on the surface of the ground but kills it as well when in the depth of its burrow. Judging from the manner in which Pepsis plunges into hole after hole-as I have observed in western Kansas-it seems not improbable that the tragedy more commonly takes place underground.



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19161 WilliamsÌÔLife-Histor of Methoca stygia Say 123 Adlerz made a few notes on the early stages and illustrates by rather poor photographs, the Methoca larva and cocoon. The latter ranged in length from 8 to 18 mm., being cylindrical, brownish yellow, composed of many layers of silk, and provided above with a sort of collar or neck.
The Champions ('14, '15) have observed the habits of this Methoca in England, where it inhabits the heathery and sandy portions of the country. The prey is the larva of Cicindela cam- pestris and sylvatica. They observed Methoca go right down the hole after her prey. The burrow is carefully filled. The wasps worked well in captivity as with Adlerz. The egg stage is about four days and the slender glassy larva matures in twenty days from oviposition.
The cocoon is dirt-free.
Bridwell (1912) speaks of Methoca californica as being "parasitic in the burrows of tiger-beetles." Aside from this statement, I know of nothing published on the habits of any of our few species. For three consecutive seasons (1913-1915) I have taken a few females of Methoca stygia in two adjoining sandy areas in Needham, a suburb of Boston, but not until the third season, when I took up- wards of twenty specimens, did I attempt to secure any biological data. The locality was but a few hundred feet in extent, and its sandy and pebble-strewn soil, a favorite haunt for various fos- sorial wasps, as Bembex, Microbembex, Bembidula, Tachytes, Tachy- sphex, Cerceris, Oxybelus, Mutilla and others, was sparsely clothed with small plants, conspicuous among which was a little sedge and an inconspicuous Hypericum. A few small colonies of Cicindelid larvae, probably C. punctulata Oliv. for the most part, undoubtedly furnished the food-supply of the Methoca progeny. This wasp is emphatically a lover of hot sunshine and was thus taken at rare intervals running in zigzag fashion over the sand. But once did I observe a Methoca attempt to enter a Cicindelid burrow and this attempt was failure because of the very small size of the aperture. Two Methocas confined in the field in glass tumblers inverted over a burrow of a Cicindelid larva yielded no results, but other experi- ments were in a degree successful.
In the summer of 1915 Methoca was comparatively abundant and twenty-six specimens were taken from August 1 toSeptember 5, fifteen of these being captured on August 15. I confined sev- eral in a quart preserve jar half filled with sand stocked with half



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124 Psyche [August
grown and nearly mature Cicindela larvae. The mouth of the jar was covered with fine gauze and the jar itself sunk in the soil in a sunny spot, to the level of the sand within. The wasps were fed sugar and water placed on flowers, and this appeared to prolong life, one Methoca living about ten days. Several of the tiger-beetle larvae had one to several (five in one case) small, orange-colored maggots attached to the body. These were probably the larvae of the bombylud fly Spogostylum, whose life-history has been partly worked out by Shelford ('13). I was unable to watch Methoca, during the greater part of the time, but did notice that while they were often careful to avoid Cicindelid burrows, at other times they would enter these and make them their abode for the night, the original occupant keeping to the bottom. In the after- noon of a very warm day I emptied the jar of its contents to find two semi-paralyzed beetle larvae each with a Methoca clinging to its venter busy malaxating, despite the rude unearthing. But their operations went no farther. On another occasion I observed Methoca putting the finishing touches to her work, in depositing grains of soil on the filled-up burrow. I obtained several eggs of the wasp. These, as also observed by the European writers, were transversely arranged in the fold behind one of the hind cox= of the cicindelid. But one egg is laid on each larva though the latter may vary greatly in size. The cylindrical egg is nearly straight, about five times as wide as long and shining transparent whitish. None hatched though this may well be due to the un- natural conditions to which they were exposed. The victims, in some cases stung so that they soon died and decomposed, in others were nearly as active as normal larvae. One of the Methoca was found decapitated a day or two after being placed in the jar. It may be well to remark that the head is very strongly attached to the thorax and indeed the whole insect is well fitted to pursue its apparently dangerous vocation. Adlerz has called attention to the shape of the metathorax which, approximately at its middle length is furrowed transversely, a place where the jaws of the cicin- delid may seize her.
The male of Methoca seems to be much rarer than the female and is probably a visitor at flowers.
The Thynnids of Australia are often of striking appearance-a female loaned me from that region is nearly an inch long and irridescent purple and bluish.




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PSYCHE, 1916.
VOL. XXIII, PLATE XII.
WILLIAMS-Life-history of Methoca stygia




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19161 Williams-Life-History of Methoca Stygia S a y 1 25 Great opportunities await the biologist who is interested in these singular insects and who has access to their haunts. More com-
plete field observations and careful methods of confinement will surely furnish a better knowledge of the habits and early stages of our own rare species.
I am indebted to Mr. C. W. Johnson of the Boston Society of Natural History, and to Prof. W. M. Wheeler and Prof. C. T. Brues of Harvard University for the loan of material. BIBLIOGRAPHY.
1836.
Say, T.
Bost. Jour. Nat. Hist., I, 3, p. 299.
1901. Sharp, D.
Camb. Nat. Hist., Insects, Pt. 2, p. 96-97. 1903. Adlerz, G. La Proie de Methoca ichneumonides Latr. Arkiv for Zoologi. Bd. 1, 255-258.
1905. Adlerz, G. Methoca ichneumonides Latr ., dess lefnadsatt- och utvecklingsstadier.
Arkiv for Zoologic, Bd. 3, No.
4, p. 1-48, 1. pi. Uppsala and Stockholm. Includes a short extract in German.
1912. Bridwell. Methoca californica. Proc. Pac. Coast. Ent. Soc. (Brochure).
1913. Shelford, V. E. The Life-History of a Bee-fly (Spogostylum anale Say) Parasite of the Larva of a Tiger Beetle (Ckin- dela scutellaris Say Var. lecontei Hald.). Ann. Ent. Soc. Am., VI, p. 213-225, 17 figs.
1914. Champion, H. G. Addendum to. Observations on the life-history of Methoca ichneumonides Latr . Ent. Mo. Mag., LI, p. 40-42, Feb. 1915.
1915.
Champion, H. G. and R. J.
Observations on the Life-
History of Methoca ichneumonides Latr. Ent. Mo. Mag. XXV, p. 266-270. Nov. 1914.
EXPLANATION OF PLATE.
All figures much enlarged.
Fig. 1. Methoca styqia 8 .
Fig. 2. Methoca stygia c? ; front view of head. Fig. 3. Methoca styqia 9 .
Fig. 4. Methoca styqia 9 ; front view of head. Fig. 5. Methoca stygia Q ; lateral view. Fig. 6. Small larva of Cicindela sp., showing egg, e. of Methoca secured behind right hind leg. Ventral view.



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