INSECTS THAT FEED ON LOCUST-EGGS. 



305 



with a very small, brown, flatteued head, with the joints near the head 

 swollen, and the hind end tapering, and with deep, translucent sutures 

 beneath the joints, which sutures show 

 certain venous marks and mottlings, 

 especially along the middle of the back. 

 It exhausts the eggs, and leaves noth- 

 ing but the shrunken and discolored 

 shells." 



This parasite has been found in Min- 

 nesota, Iowa, Kansas, and Missouri, 

 and in 1876 destroyed about one per 

 cent, of the eggs. The following let- 

 ters refer to it : 



Fig. 37. —Undetermined egg-parasite 

 OF EocKY Mountain Locust. 



The other day, as I was strolling through the fields, I stopped to examine some eggs. 

 I found the ground in spots quite full of white grubs, worms or maggots, whatever 

 they may be called. Many of them were in the egg-pods, busy at work. I collected 

 a few, and sent to you in a small vial by mail for your examination. The ground was 

 hifh and dry where found. — [S. D. Payne, Kasota, Le Sueur County, Minn., Septem- 

 ber 28, 1876. 



I think the Silky Mite has done good service in destroying eggs in one or two coun- 

 ties, particularly Nobles. But we are getting, in addition, continual newspaper reports 

 of white grubs destroying the eggs. I started out to see for myself, and have found 

 a number, which I send you. — [A. Whitman, Saint Paul, Minn., September 7, 1876. 



Though we have endeavored to rear quite a number of them to the 



perfect state, we have met with no success. The characters of the grub 



show it to be Hymenopterous, and probably of the family Ichneumon- 



idse. It hibernates in various stages of growth, and we have found the 



larva unchanged throughout spring and early summer, and have kept 



a few alive from the fall of 1876 to September, 1877, all dying in the 



end unchanged and without spinning a cocoon. The larva of Pimpla 



instigator is said by Motchulsky to prey on the eggs of European locusts. 



ICHNEUMONiD (?) Larva. — Average length, 0.50 inch. Body curved, glabrous, tapering 

 posteriorly, swollen anteriorly. Color opaque whitish, with translucent yellowish mot- 

 tlings, and some venous marks at sutures, especially along medio-dorsum. Sutures deep. 

 A lateral row of swellings. Head small, flattened, dark brown, in five pieces, consisting 

 above or a frontal ovoid piece and two lateral pieces of somewhat similar form, and 

 each beariug near tip a minut?, two-jointed palpus; beneath of two broad, subtriangular 

 jaws, having forward and lateral motion, and each, also, bearing near the center, in a 

 depression, a two jointed feeler. A spiracle each side in a fold between joints 2 and 3, 

 and another on each side of the penultimate joint, 12. None otherwise perceptible. 



Miscellaneous Species. — In addition to the foregoing insects that 

 attack the eggs, different species of ants have been reported to do 

 so to some extent. We have also found certain Myriapods, and espe- 

 cially a species of Mecistocephalus within the egg-mass, and have wit- 

 nessed the common White Grub (larva of Lachnosterna fusca) actually 

 feeding upon the eggs, thus giving another conclusive proof that an 

 essential vegetable feeder will exceptionally take to soft animal food. 



Mr. S. H. Scudder (Proc. Bost. Soc. Nat. Hist., vol. xii, p. 99) has re- 

 corded the rearing of a Ohalcid-fly (Fig. 38) from the eggs of the Carolina 

 locust; and we have received from R. B. Potts, Worthington, Minn., an 

 20 a 



