ACETARIACEOUS PLANTS. — THE LETTUCE. 



157 



Their merits Lave, however, attracted little at- 

 tention in Britain. The French profess to have 

 several kinds in the seed-shops, which they 

 consider adapted to the purpose of growing to 

 be cut young, as we do mustard and cress. 

 These they call Laitue chicoree, Laitue a cou- 

 per, Laitue epinard. Any sort of the upright 

 or cos varieties will do equally well. 



Diseases and insects. — Among the latter are the 

 lettuce-fly (Anthomyia lactucce Bouch.), the larvte 

 of which, according to Ruricola, in " Gardeners' 

 Chronicle," make their appearance in August, 

 but more abundantly in September. They are 

 not very readily distinguished from those of the 

 cabbage and turnip, being of a yellowish-white 

 colour, tapering towards the head, which is 

 pointed, and armed with two short black claws 

 at the nose. These maggots live in the involucra 

 of different varieties of lettuce, feeding upon the 

 seed and receptacle ; and when they have de- 

 voured these, they push themselves out back- 

 wards, either to enter another seed-vessel, or 

 fall to the ground to become pupse. When the 

 seed stems are gathered and dying, the larvas 

 change to pupse, being bright chestnut coloured ; 

 oval cases, which are rough when examined 

 under a lens, with two minute tubercles at the 

 head, and two hooks and a few other tubercles 

 at the tail. In May a few of the pupse hatch, 

 although they are sometimes found as early as 

 April and as late as July. The male fly is intense 

 black, clothed with short hairs and bristles ; the 

 eyes reddish brown, and meeting above ; face 

 inclining to chestnut colour, with a bright spot 

 of the same on the crown ; the fore part of the 

 trunk bears four varying whitish stripes; the 

 body is ashy grey ; the segments blackish, at 

 the base a deep black ; wings, two, stained with 

 black and beautifully irridescent ; the base and 

 poisers ochreous; the nervures of the wings 

 pitchy. The female is entirely ashy grey, and 

 less bristly ; the eyes not meeting on the crown, 

 with a bright chestnut-coloured stripe between 

 them ; body oval ; the apex cone-shaped ; horns 

 and legs blackish ; wings and nervures lighter 

 than in the male, which it equals in size. 



The Arctia caja — Euprepia caja of others — 

 fig. 57 (the garden tiger-moth), appears in July, 

 and often commits sad havoc upon lettuce 

 crops, and also on strawberries. The caterpillar 

 is one of the most voracious of all its class, eat- 

 ing double its own weight per day. They do not 

 eat the solid part of the leaf, but suck out the 

 juice, and thereby destroy the plant as com- 

 pletely as others do who devour the leaves and 

 stems. It has been ascertained that one of these 

 caterpillars, weighing 36 grains, voided daily 

 more than 1 5 grains' weight of excrement ; yet 

 its own weight only increased 2 grains daily. The 

 caterpillar of this moth is to be found in June, 

 and the perfect insect in July, so that its period 

 of voracity is providentially not of long dura- 

 tion. It is well known in gardens in its perfect 

 state, and may be readily captured while on wing 

 by using an entomologist's net. Hind wings 

 bright red, with blue-black spots ; fore legs of a 

 reddish brown, marked with creamy white ; 

 thorax brown, with a red neck-band ; abdomen 

 red, with blue-black bars. The caterpillars are 

 VOL. II. 



dark brown, thickly covered with reddish-brown 

 hairs. They cast their skin quite entire, and 



Fig. 57. 



tfif 



TIGER MOTH AND CATERPILLAR. 



these may be frequently picked up in mistake 

 for the living insect. 



Another enemy to the lettuce, as well as many 

 of the products of the garden, is the Tipula ma- 

 culosa of Hoffmansegg (the spotted garden-gnat), 

 fig. 58. The grubs 

 Fig. 58. of the genus Ti- 



pula are amongst 

 the worst ene- 

 mies to gardens. 

 It would appear 

 that, until lately, 

 we had no cor- 

 rect idea of the 

 number of species 

 by which we are 

 infested — Tipula 

 oleracea apparent- 

 ly bearing the 

 whole blame of 

 the injury done 

 us by his family. 

 Ruricola, in "Gar- 

 deners' Chro- 

 nicle," 1846, p. 

 317, appears to 

 have drawn at- 

 tention to this 

 species, and de- 

 scribes them as 

 follows : " These 

 larvae are of the 

 same dirty earth 

 colour as those of 

 T. oleracea; but 

 they are only 

 three-fourths of 

 an inch long, and as thick as a large crow-quill. 

 They are wrinkled, and when at rest contract 

 themselves, drawing in the head and thoracic 

 segments, so that this portion looks more like 

 the anal extremity : the animal, however, is 

 able to thrust out its head and crawl along very 



X 



SPOTTED GARDEN-GNAT OR CRANE 

 FLY, GRUB, AND PUPA. 



