210 



The Dictionary of Gardening, 



Potato — continued. 



form, with small eyes ; flesh white and floury when cooked ; an 

 abundant cropper, very handsome, tine for exhibition, and ex- 

 cellent for general use. Scotch Chami'ion, a good main crop 

 variety, a heavy cropper, and very free from disease. Vicar 

 OF hAi.EHAM, a very ttne and distinct variety, seedling from 

 Victoria ; the tubers are purple, round, and of very handsome 

 shape, with beautiful white flesh, of first-rate table quality, and 

 fine for exhibition purposes. 



POTATO BEETLE (Doryphora decemlineala). This 

 insect, also often called the Colorado Beetle, though not 

 yet a resident in the British Islands, is among the best 

 known of insects, by name, at least, to most persons in the 

 United Kingdom, thanks to the scare that arose with 

 regard to it a few years ago. It was first observed in 

 the Rocky Mountains of America, in the Colorado region, 

 feeding on a wild species of Solanum, the genus to which 

 the Potato belongs. When Potatoes were planted by 

 settlers in the beetle's native home, it attacked the new 

 food-plant, throve on it only too well, and commenced 

 to spread rapidly eastward ; and in 1876 it reached the 

 Atlantic coast. It is now common along the Eastern 

 States, and in Canada, and it is not impossible that it 

 will be conveyed to, and may be able to establish itself 

 in, our own islands. It has proved able to withstand 

 heat and cold, dry and moist climates ; and would pro- 



FiG. 261. Potato Beetle (Donjphom decemlineata), natural size. 

 bably find onr climate suit it. In its passage eastward 

 in America, it committed great havoc in the Potato- 

 fields, and excited fears in the minds of many, lest it 

 should continue, year by year, to inflict severe injury to 

 the Potato crop, and lest it might effect a footing in 

 Britain, as appeared very probable. To guard against 

 this latter risk, the Privy Council of Great Britain and 

 Ireland passed an Order, which was published in the 

 "London Gazette" of August 17th, 1877, to the effect 

 that " If the owner of, or any person having the charge 



Potato Beetle — continued. 

 beetle may be obtained from Pigs. 261 and 262, and of 

 the larva from Fig. 263. The colours of the beetle are 

 as follows : It is usually straw-yellow above, though, at 

 times, the head and thorax are tawny-yellow, with black 

 spots on them, as shown. The wing-cases each bear five 

 equidistant, black bands, the second and third of which, 

 counting from the middle, frequently meet behind. The 

 legs are tawny-yellow, with black knees and tarsi, and 

 (in, at least, the last pair) black thighs; the antennse 

 are yellow in their basal part, black in the rest of their 



Fig. 263. Larva of Potato Beetle (Dorinjhora deceinlineata), 

 natural size. 



length. The larva (see Fig. 263) is pale yellow, or, rather' 

 dusky-yellow, or freckled with minute black dots on the 

 back; and there are tn-o rows of larger black dots along 

 each side ; the legs are black. The females place their 

 eggs in small clusters on the lower surface of the 



Fig. 262. Potato Beetle (.Dorijplwm decemUneata), enlarged. The 

 has been removed to show the wing. 



of, any crop of Potatoes, or any vegetable, or substance, 

 finds, or knows to be found, thereon the Colorado Beetle, 

 in any stage of existence, he shall, with all practicable 

 speed, give notice of the same to a Constable of the 



Police establishment of the locality ; and it is 



further provided that it shall not be lawful for any person 

 to sell, keep, or distribute living specimens of the Colorado 

 Beetle in any stage ; and any person failing to do any- 

 thing he is by this Order required to do, is, for each 

 offence, liable to a penalty not exceeding ten pounds." 

 An idea of the general form, size, and markings of the 



Fig. 261. Eggs of Pot.ito Beetle on a Leaf, natural size. 



Potato leaves (see Pig. 264). The eggs are oval, smooth, 

 bright yeUow, and glossy. In five or six days, the larvae 

 appear, and in from two to three weeks 

 they are full - fed, and creep under 

 ground, to become pupa3. In about a fort- 

 night, the beetles emerge, and the fe- 

 males proceed to egg-laying. In America, 

 three broods are produced each year, the 

 third brood hybernating under ground, 

 or in any suitable retreat. Both larva- 

 and beetles feed on the leaves of Po- 

 tatoes, and soon leave nothing but 

 the mere ribs, utterly destroying the 

 crop. 



In June, 1877, the insect was found 

 at Miihlheim, on the Rhine, and in three 

 places at Schildau, in Prussian Saxony ; 

 but it was stamped out by the energetic 

 action of the Prussian Government. Oc- 

 casional living examples have been found 

 in British seaports, but they have never 

 appeared in this country on the Potato 

 crops. In America, and in Germany, it 

 has been observed that, when they have 

 exhan.sted the Potato-plants, they resort 

 to low weeds, e.g., Goosefoot, Knotgrass, Hedge Mustard, 

 and even to Cabbage. 



Remedies. In America, the use of Paris Green, or 

 Scheele's Green (hydrocupric arsenite), sold at about 6d. 

 per lb., is found effectual in saving the crop of Potatoes. 

 It may be dusted on the plants, but it is better to mix it 

 with water, in the strength of a tablespoonful to a bucket 

 of water, and to sprinkle them with this. Caution must 

 be used in handling this substance, as it is a dangerous 

 poison. Hand-picking would probably be sufficient to 

 get rid of the insects on their first appearance in a new 



left wing-case 



