22 



Potato Ctilture. 



also the honey locusts, and especially 

 the Windsor bean. In particular years 

 it has been known, in conjunction 

 with the rose-bug, ( Macrodactylus sitb- 

 spinosuS) Linn.,) to swarm upon every 

 apple-tree in some orchards in Illinois, 

 not only eating the foliage, but gnaw- 

 ing into the young apples. 



This beetle does considerable da- 

 mage to the potato crop, especially in 

 the North- Western States. Like the 

 other members of the (Lytta) family, 

 it lives under ground while in the 

 lava state, and is troublesome only 

 when in the perfect or winged state. 



The Black Rat Blister-Bee- 

 tle, (Lytta murina, Le CSnte.) This 

 species (Fig. 8,) is entirely black. 

 There is a very similar species, the 

 black blister-beetle, (Lytta atrata, 

 Fabr.,)from which the black-rat blister- 

 beetle is distinguishable only by hav- 

 ing four raised lines placed length- 

 wise upon each wing-case, and by the 

 two first joints of the antennae being 

 greatly dilated and lengthened in the 

 males, of the lath species. It is 

 asserted by some authors that the 

 black blister-beetle is injurious to the 

 potato ; but I can not see how it could 

 do much damage to that crop, as the 

 perfect insect does not appear until 

 late in August, when the potato crop 

 is nearly out of its reach. Not so, 

 however, with the black-rat blister- 

 beetle, which is on hand ready for 

 business early in the season. This 

 insect does considerable damage to 

 the potato in Iowa, and neighboring 

 States ; it is also found, though in not 

 so great numbers, throughout the 

 whole of the Northern States. 



The Margined Blister-Bee- 

 tle, (Lytta marginata, Fabr.) This 

 species (Fig. 9) maybe at once recog- 

 nized by its general black color, and 

 the ash-gray edging to its wing-cases. 

 It usually feeds on certain wild plants, 



I but does not object to a diet of po- 

 tato-leaves. Though' found over a 



| large extent of country, it seldom 

 appears in numbers large enough to 

 damage the potato crop materially. 

 Like other blister-beetles, it goes un- 

 der ground to pass into the pupa state. 

 and attacks the potato only when it is 

 in the perfect or winged state. 



The Three-Lined Leaf-Bee- 

 tle, (Lema trilineata, Olivier.) The 

 larva of the three-lined leaf-beetle may 

 be distinguished from all other insects 

 which prey upon the potato by its 

 habit of covering itself with its own 

 excrement. In Figure 10, #, this larva 

 is shown in profile, both full and half 

 grown, covered with the soft, greenish 

 excrementitious matter which from 

 time to time it discharges. Figure 10, 

 c, gives a somewhat magnified view 

 of the pupa, and Figure 10, /;, shows 

 the last few joints of the abdomen of 

 the larva, magnified and viewed from 

 above. The vent of the larva, as 

 will be seen from this last figure, is 

 situated on the upper surface of the 

 last joint, so that its excrement natu- 

 rally falls upon its back, and by suc- 

 cessive discharges is crowded forward 

 toward its head, till the whole upper 

 surface is covered with it. There are 

 several other larva, feeding upon other 

 plants, which wear cloaks of this 

 strange material. 



Many authors suppose that the ob- 

 ject of the larva in all these cases is to 

 protect itself from the heat of the sun. 

 In all probability the real aim of na- 

 ture in the case of all these larvae is 

 to defend them from the attacks of 

 birds and of cannibal and parasitic in- 

 sects. 



There are two broods of this insect 

 every year. The first brood of larvae 

 may be found on the potato-vine to- 

 ward the latter end of June, and the 

 second in August. 



The first brood stays under ground 



