43 



3rd of May ; from that date until the end of June they were very abundant, and from 

 the careful examination of many seed-heads towards the end of that month it was- 

 estimated that, while five-sixths of the clover seed had been destroyed by the midges, 

 four-fifths of the midges had been destroyed by this parasite. Thus through the good 

 offices of this one species of parasite the prospective numbers of the next brood of midget 

 were reduced to the extent of 80 per cent. 



The second parasite, P. error, develops more slowly, and remains within the body of 

 the midge larva until after it has escaped from the clover head, entered the ground, and 

 spun its cocoon ; then the full-grown parasite, having destroyed its host, eats its way 

 through the cocoon and escapes. This has been found as yet only in specimens of the 

 midge larva received from Yates County, New York State. 



THE CLOVER ROOT-BORER— ^2/^as^«« trifolii, Muller. 



This is another new pest — a small beetle about one-twelfth of an inch long, belonging 

 to the family usually known as Bark-borers, Scolytidce, from their habit of boring irregular 

 channels through the inner bark of various trees. This species, however, is a root-borer. 

 The beetle is of a reddish-brown colour, coarsely punctured on the body, not so coarsely 

 punctured on the head and thorax, with the whole body more or less hairy. They usually 

 reach maturity in October ; and the beetles hibernate in the root and probably live upon 

 the root. Early in spring they leave their hiding-places, and, after pairing, the female 

 proceeds to deposit her eggs. 



The insect in its various stages is represented in the accompanying figure, 15 : 

 d shows the beetle ; 6, the larva as found in the burrows ; c, the pupa, which is usually 

 found lodged in a cavity at the bottom of the burrow ; the figures are about ten times 

 their natural size. At a a «, the destructive work of the larvae on the roots of the clover 

 is shown. 



How AND Where the Egg is Deposited. 



The female bores a large cavity in the crown of the root, and there deposits from four- 

 to six pale- whitish elliptical eggs, which hatch in about a week. 



The Larva, or Grub. 



The young larvae at first feed in the cavity made by the 

 parent until it is enlarged to the size of a small pea ; then they 

 begin to gnaw sideways and downwards, probably because the 

 lower and more tender portions of the root are more suitable 

 for their nourishment than the upper woody portions. The 

 burrows run in a nearly straight line, and lie between the 

 outer skin and the woody centre of the root, and are filled 

 with black excremental dust. When full-grown the larva 

 (6, fig. 15) is a little over one-eighth of an inch long, of a 

 dingy white colour, with a pale yellow head and brown man- 

 dibles. Although the perfect beetle is believed to feed on the 

 clover roots, it is in the larval condition that this insect 

 most destructive, working more particularly on the larger 

 roots — in many instances entirely severing them at the surface 

 of the ground — and this to such an extent that at times it is 

 found extremely difficult to cut the clover, owing to the ease 

 with which the plant is pulled up before the mower. "Up to 

 the time of frost Prof. Riley has found the insect in all 

 staiges of growth, but at this time the perfect beetles are most 

 numerous. 



The Pupa, or Chrysalis. 



The pupa (c, fig. 15) occupies a smooth cavity at the end of the gallery or chamber 

 excavated by the larva. Here, at the end of September, it is to be found with its head 

 upwards, and if the season is favourable most of the beetles escape in October. 



Fig. 15. 



