Clovek Insects G91 



legs yellowish brown. At least fifty per cent of the crop is, on 

 the average, annually destroyed by this pest. The clover-seed 

 chaleid is also the most serious pest with which the grower of 

 alfalfa seed has to contend. 



On closie examination the flies will be found on the clover heads 

 throughout the season. The female is provided with a sharp 

 needle-like ovipositor with which she inserts an egg through the 

 floral envelope directly into the kernel of the unripe seed. This 

 minute egg has a remarkable shape, l^eing broadly ovate and pro- 

 vided with a long slender pedicel or handle about twice as long 

 as the egg. From the egg there hatches a small grub that devours 

 the entire contents of the seed and when mature (Fig. 662, b) 

 occupies nearly the whole cavity. Pupation takes place within the 

 seed and the adult fly emerges by gnawing a small, round hole 

 through the sieed-ooat. Infested seeds have an abnormal appear- 

 ance, being dnll brown, often misshapen, and a little luidersized. 

 The insect may reach maturity and the adults emerge from the 

 seeds within three weeks after the eggs ai*e laid, but the period 

 is usually much longer. Emergence is very irregular, depending 

 in large measure on the conditions of temperature and moisture. 

 It has been found that the adults appear in maximum abmi dance 

 in June and again in August. From eggs laid by the June 

 brood of flies adults will continue to emerge from July through- 

 out the remainder of the season and some will hold over until the 

 following May and June. The greater proportion, however, 

 emerge during August of the same year. From eggs laid in 

 August some adults will emerge the same season, but most of 

 them do not emerge until the following spring and a few may not 

 emerge until the following August. 



.Control. If the grower intends to harvest a crop of clover 

 seed the first crop should bo cut rather early, as soon as the field 

 comes into bloom, so as to [)revout the (]eveloi)meiit of a large i)ro- 

 jTiortion of the early brood of insects and tlius decrease the size 

 of the second brood. If the newly seeded clover has a heavy 

 bloom it would pay either to cut or pasture this oft" in the fall in 

 order to reduce the number of chalcis flies emerging in the field 

 the following spring. 



