PACHYGASTRIA TRIFOLII. 19 



Comparison of Pachygastria eversmanni with P. trifolii 

 and its varieties. — Christoph compares (Stett. Ent. Zeit., xxviii., pp. 

 240 — 242) P. eversmanni with P. ti'ifolii and states that although he 

 did not wish to compare the former with the varieties of the latter to 

 prove the specific distinctness of the former, yet P. eversmamii showed 

 no transitions to P. var. medicaginis, &c, adding, however, that " so 

 long as that distinctness depends on a comparison of the imagines of 

 these two related species, so long will P. eversmanni be not recognised 

 generally as a distinct species." He, however, goes on to say that he rears 

 the larvae every year, and this stage alone will give eversmamii specific 

 right. Apart from the altogether different aspect of the larva, its mode 

 of life differs very considerably from that of P. trifolii. The imago 

 flies in August and first half of September on dry salt steppes. In the 

 latter half of April and in early May, in rather circumscribed localities 

 on the steppes, the young (and at most not half-grown) larvae are to be 

 found sitting on the bare earth, and less frequently on the stems of 

 plants. The young larvae at first feed exclusively on young leaves of 

 the hard steppe-grasses, but later refuse this food and are to be reared 

 only on various leguminous plants, e.g., Astragalus oiwbrychis, although, 

 where the larvae are found, with the exception of Alhagi camelorum, 

 such plants do not grow, and the habits of the larvae in captivity give 

 no clue to their habits in the open ; he has never been able to find a full- 

 grown larva of P. eversmanni in nature, and he thinks that they possibly 

 retire into the cracks in the ground, often a foot in depth, during the 

 daytime, coming out to feed by night. The larvae of P. trifolii are 

 never to be found in the same localities with those of P. eversmanni, 

 whilst they also feed exposed until full-fed, and are easy to find. The 

 larva is described as : 



About 70 mm.* long and 8 mm. wide; the head-hemispheres a fine blue-grey; 

 the middle of the head above the mouth-parts yellow-grey, with a short black longi- 

 tudinal streak, the latter red-yellow. The segmental incisions of a fine light blue. 

 The " head-segment " is bright cherry-red above, margined with yellow-red anteriorly. 

 On the next two segments are found dorsally, on each side, two large not distinctly 

 defined spots of like colour. Along the dorsum runs a whitish band, only distinctly 

 white between the incisions ; then follows, as a continuation of the already mentioned 

 red lateral spots, a band (often interrupted by the blue-grey ground colour) bounded 

 towards the sides with velvet-black also only in patches. This black shades, towards 

 the venter, into grey and reddish-grey (almost flesh-colour). On the second and 

 third segments the black is sharply cut off before yellow-white spots, decreasing 

 towards the venter into fine dots ; on the next two segments two short obliquely-placed 

 stripes run from the black towards the legs, without, however, reaching them ; on the 

 following segment is found, instead of the third oblique line, only an elongated white 

 spot. Venter and legs bright red-yellow ; between the legs the red-yellow is enclosed 

 by somewhat broad black rings. The fine yellow-grey hair is somewhat longer than, 

 but just as dense as, in P. trifolii. The larva is of uniform thickness throughout, 

 rather more slender than that of P. trifolii, and the fine hair is more equal in length 

 than in the latter. 



It must be confessed that the life-histories of the two insects run 

 very parallel. We still await a critical comparison of the larvae, the 

 mere description being of little value in determining the matters of 

 detail on which specific identity (or the reverse) must be decided. 



Egg-laying. — There appears to be some doubt as to whether or 

 not the eggs are attached. Some sent to us by Mr. Edelsten were laid 

 on a sprig of heather, several on the same sprig, and two or three 



* Christoph's note says 7 mm., an obvious misprint. 



