THE AMERICAN ENTOMOLOGIST. 



43 



tious and stages of its existence; Fig-ure 34 

 b, b, of that of the bogus Colorado Potato- 

 bug. It will be seen at once that the head 

 of the former is black, that the first joint 

 behind the head is pale and edged with black 

 behind onl)', that there is a double row of 

 black spots along the side of the body, and that 

 the legs are black. In the other larva (Fig. 34 &), 

 on the contrary, the head is of a pale color, the 

 first joint behind the head is tinged with dusky 

 and edged all round with black, there is but a 

 single row of black spots along the side of the 

 body, and the legs are pale. Take a hundred 

 full-grown specimens of the former larva, and 

 you will find them all to present the above char- 

 acters. Take a hundred full grown sjoecimeus 

 of the latter larva, and precisely the same rule 

 will hold good.* 



• We subjoin a teohnioal description of tlie larva otDorij- 

 phorajuncta. Tliat of the larva ot Boryphora 10-lineata will 

 be found in Dr. Fitch's N. T. Reports, Vol. lU, pp. 231-3. 

 According to Dr. Fitch, the ground-color of this last larva is 

 ' 'pale yellow' ' in the mature state ; according to Dr. Shimer, 

 in his excellent article on the preparatory stages of this in- 

 sect, it is ' 'orange. ' ' We ourselves should prefer to desig- 

 nate it as cream-color, more or less tinged with Venetian 

 red; and we think we have observed that the mature larva; of 

 the earlier broods are more sti'ongly tinged with this color 

 than the mature larvaj of the later broods . In the iimnature 

 state the ground-color of the larva is a dull Veneti.in red. 



DOEYPHORA JUNCTA, Germar; matm-e larva .—General 

 color a pale yellowish flesh-color. Head, with the autennie 

 l)laced behind the base of the mandibles, short and very ro- 

 bustly conical, three-jointed, joints 2 and 3 black. Precisely 

 as in W-lineata, there are six small simple black eyes upon 

 each side, one pair longitudinally arranged and placed be- 

 low the antenna, the other two pairs arranged in a square 

 and placed a little above and behind the antenna ; tip of the 

 mandibles dusky. £ody, with the dorsum of joint 1 com- 

 posed of a, separate transverse horny plate, rounded at the 

 sides, tinged more or less with dusky, and broadly edged 

 all roiuid with black. .Joints 1—3 each with a lateral horny 

 black tubercle, that of joint 1 placed below and behind the 

 homy prothoracic plate, and enclosing a spiracle. Joints 

 4—11 each with a similar lateral tubercle enclosing a spiracle ; 

 but the row composed of these eight tubercles is placed a 

 little above the row of three tubercles on joints 1—3, and the 

 last four of the eight are gradually smaller iind sra.aller, 

 until that on joint S is reduced to a simple black spiracle ; 

 dorsum of joints 8 and 9 dusky. Legs pale yellow; cox.-e 

 exteriorly a little dusky, the two hinder pairs each more and 

 more so, with a geminate homy plate above each, which is 



Now let us see what are the differences in the 

 perfect beetle state of these two insects, in which 

 state even a practised entomologist would, at 

 first sight, be apt to confound them together. 

 Indeed, so minute are the diflcrences, that in a 

 drawing of the natural size it is scarcely possible to 

 exhibit them, and in order to do so we have been 

 compelled to greatly magnify the wing-case and 

 the leg of each species. Figure 33 d, d exhibits the 

 Ti-ne Colorado Potato-bug ; Fig. 31 c the Bogus 

 Colorado Potato-bug, each of its natural size. 

 Fig. 33 e shows the left wing-case enlarged,' 

 and Fig. 33/au enlarged leg of the former ; Fig. 

 34 a the left wing-case enlarged, and Fig. 34 

 e an enlarged leg of the latter. On a close 

 inspection it will be perceived that in the for- 

 mer (Fig. 33 e) the boundary of each dark 

 stripe on the wing-cases, especially towards the 

 middle, is studded with confused and in-egular 

 punctures, partly inside and partly outside the 

 edge of the dark stripe ; that it is the third and 

 fourth dark stripes, counting from the outside, 

 that are united behind ; and that in the leg both 

 the knees and the feet are black. In the latter 

 (Fig. 31 cZ), on the contrary, the dark stripes are 

 accurately edged by a single regular row of 

 punctures placed in a groove (stria) ; it is the 

 second and tliird stripes — not the third and 

 fourth — counting from the outside, that are 

 united behind, the space between them being 

 almost always brown ; and the leg is entirely 

 pale, except a black spot on the middle of the 

 front of thetliigh. 



The spots on the thorax, in either of the 

 above two species, are normally eighteen in 

 number, arranged in the same very peculiar 

 pattei-n which may be seen both in Fig. 33 d, d and 

 in Fig. 34 c ; and precisely the same variations in 

 this complicated pattern occur in either species. 

 These are certainly very remarkable and sug- 

 gestive facts ; and the reader who desires to see 

 them more fully tliscussed is referred to a passage 

 in a scientific paper, published in 1865, by the 

 senior editor.* 



After all these statements, it will not be won- 

 dered at that several otherwise well qualified 

 observers have imagined that they had captured 

 the true Colorado Potato-bug in Illinois long 

 previously to the year 1864. Many such cases 

 have been carefully investigated, and in every 

 one of them it has turned out, upon examining 



more .and more dusky in each successive pair . An exterior 

 dusky dot, or small spot, on the tip of the femur and of the 

 tibia. Tarsus small, onc-jointcd, dusky, and with a black 



* Proceedings of the Entotnological Socielij of Philadelphia, 

 Vol. VI., pp,207-S, 



