ESCULENT-ROOTED PLANTS.— THE TURNIP. 



195 



not visible on the upper side of the leaf. They 

 often attack plants in greenhouses. The only 

 way we know of is to pick off the leaves as soon 

 as the insect appears to have attacked them, 

 and to burn them. The larvae of this insect are 

 devoured in vast numbers by the Ceraphron 

 niger and Microgaster virides. 



Noctua exclamationis and N. segetum (the heart 

 and dart moth, fig. 71, and common dart-moth, fig. 



Fig. 71. 



HEART AND DART MOTH AND CATERPILLAR. 



Natural size. 



72). These insects appear to be either increas- 

 ing of late years, or more probably their economy 

 is now better understood than formerly. They 



Fig. 72. 



COMMON DART-MOTH, CATERPILLAR, AND CHRYSALIS. 



Natural size. 



are of the class called surface caterpillars, or 

 surface grubs, and are exceedingly destructive 

 to various crops, particularly to turnips, pota- 

 toes, and mangold-wurzel. They commence 

 hostilities upon the turnip in July, by eating off 

 the crowns. They afterwards attack the bulbs, 

 and render them unfit for use. In June they 

 attack the mangold-wurzel by eating off the 

 roots immediately under the surface of the 

 ground, and they attack the potato when just 



pushing above ground. They seem to feed by 

 night, and towards morning carry away portions 

 of the leaves, which they drag into holes, so that 

 they may feast upon them at leisure and in 

 safety. Like rabbits, they seem to take a plea- 

 sure in cutting over the tops from mere wanton 

 mischief, as they have been detected decapitating 

 plant after plant, without waiting to eat the 

 same. 



"Where the eggs of N. exclamationis are 

 laid has not been recorded ; but it is stated that 

 the moth of N. segetum deposits hers in the 

 earth. The caterpillar of the former is some- 

 what cylindrical, but a little depressed above, 

 having six pectoral, eight abdominal, and two 

 anal feet. It is of a dull lilac colour, with a 

 broad pale strip down the back, the margins of 

 which form a darker line along each side, and 

 there is a double dorsal line extending the whole 

 length. The head is horny and brown; the 

 minute eyes, and two curved lines, as well as 

 the jaws, are black. The first thoracic segment 

 is rather horny and dotted ; the following seg- 

 ments have four little tubercles on each, pro- 

 ducing hairs, as well as similar ones on the 

 sides. The stigma is black. When full fed, it 

 is an inch and a half in length, and buries itself, 

 forming an oval cell of the earth, in which it 

 changes to a shining rust - coloured chrysalis, 

 to pass the winter in; and the following June, 

 or perhaps earlier, the moth hatches." The 

 moth " is of a clay colour, the wings reposing 

 horizontally ; the horns are like bristles, but 

 slightly pectinated in the males ; the tongue is 

 long; on the front of the thorax is a transverse 

 dark patch; on the upper wings there are two 

 waved lines near the base ; to the second is at- 

 tached a long, longitudinal, deep-brown streak ; 

 above it is a spot varying in size and form, and 

 beyond it a large kidney-shaped one; then follows 

 a transverse, pale, waved line ; and near the cilia 

 is a more irregular one. The under wings are 

 white, the upper margin and nervures brown; 

 but in the female the wings are entirely dark 

 brown ; their expanse is 1\ inch. The caterpil- 

 lar of N. segetum" (or Agrotis segetum of Curtis) 

 " is more cylindrical than the foregoing species ; 

 the sides are greener, and there are three black 

 dots on the stigma." An excellent description 

 of it will be found in the "Koyal Agric. Journ.," 

 vol. iv. p. 106. Ruricola, in " Gardeners' Chron.," 

 1844, p. 619, from whose excellent paper the 

 substance of the above is taken, suggests, as re- 

 medies, salt-water, lime-water, and an infusion 

 of tobacco, as being distasteful to these grubs, 

 and also soot applied to the surface early in the 

 year, and laid on an inch in thickness. " One lb. 

 of soap, dissolved in 16 gallons of soft water, 

 and applied warm to the infested ground, espe- 

 cially round the roots, the surface caterpillars 

 will dart out of their burrows, and may thus be 

 readily collected ; but no time must be lost, as 

 they will retire under ground as soon as its 

 effects have subsided." The use of hot water 

 has been too little hitherto understood in the 

 destruction of insects. It may be applied at 

 nearly the boiling point to most plants without 

 injury to them, but with manifest effect upon 

 insects, particularly grubs, whose skins are thin 



