THE EUROPEAN HOESE-RADISH WEBWORM. 



THE EGG. 



Y 

 -*'*i* 





■•^■. 





The eggs (fig. 2) are deposited in compact masses containiii^^ from 

 half a dozen eg^s to a score or more. Both the egg and the mas:> 

 are difficult to describe, the individual 

 egg being scarcely separate from the 

 mass. 



The individujil ess is iiTeguhu" oval, the 

 mass heins ai'fiuifred more or less irregiUarly, 

 as in tl»e case of m Iioneycomb. Tlie color is 

 a little brighter green than the leaf on which 

 it is deposited and each egg is snrrounded hy 

 an irregnlar ring of yellow spots arranged 

 in chains numbering about 12 to 18 to an 

 egg. There is strong overkipping, so that an 

 egg mass resembles, very imperfectly, a mass 

 of fish scales. The surface is finely reticulate 

 and divided into shining, minute, irregular 

 areas nuich like the surface of leather. The 

 diameter is about 0.8 mm. 



THE LARVA. 



Fig. 2.— European horse-radish wcb- 

 worm : a. Egg mass in situ on leaf, 

 three times natural size ; h, sec- 

 tion of surface of egg, hiirhly mag- 

 nified. 



In the penultimate stage the larva (fig. 3) 



presents an appeai'ance somewhat similar to 



the fuU-gi-own larva as regards the arrangement of the piliferous tubercles, 



but the form is more slender and the body tapers more at each end (the head 



being proportionately much smaller). The general color 



of the upper surface is purplish and has the peculiar ap- 



])ea ranee of being split through the middle, due to a wide 



]>inkis]i longitudinal liand separating the two jiai'ts lH>tween 



llie rows of piliferous tu!)ercles. The thoracic and anal 



]ila1es are correspondingly smaller and faint yellowish 



brown. 



Thk FUI>I.-(tKOWX T.akva. 



Tlic full-grown larva {Ivj:. 1) is eloiigale, cylindi-ical. iilioul 

 six linii>s as long ;is \vi(l(>, juid tapers slightly (owai'd cadi 

 ext rviiiily, espccin llv pnsh-riorly. The general rolor is 

 variable. g(>nerally cither dull oi- shining (l:;rk slate gr;i\ 

 above, sometimes faintly bluisli. The lower surface is jialc 

 gi'cenisli yellow or yellowish, and the sides are marked 

 with a narrow stigniatal line. orang(> about tlu> spiracles 

 and wbitisli or ycllowisli nc;ir tlic sutures. The head is 

 shining jet black, faintly but distinctly sei»araled, the delta- 

 shaped nuddle poi'tion longer than wide. The thoracic plati" 

 is piceous, the middle third or fourth paler, sometimes 

 yellowi.sh. The abdominal segments are without trace of 

 transverse stripes: the piliferous tubercles are large and 

 black; two paii's on the first two segments, the remainder 

 arranged in groups of three, each side forming a triangle. 

 The anal plate is small, dull pale brownish. The sides have 

 a row -if substigniatal tubercles, one or two on each segment and another row 

 nndway between these and the legs; the legs are greenish or yellowish. 

 The length is IS r.nn. : the width, ;' nun. 



Fig. 3. — European 

 horse-radish wol)- 

 worm : rciiulti- 



luatr stML,'!' (if 

 larva. Ahich imi- 

 largod. 



