138 



CEKEAL AND FORAGE INSECTS. 



of the stem, remaining over or close to several punctures, indicating that a single 

 individual may make several punctures and take the sap that accumulates in all of 

 them. Punctures in a case of this kind are not over one-sixteenth or one-eighth of an 

 inch apart, and from two to four are found in each group. We are inclined to think 

 that the punctures are made purposely for securing the sap and not for devouring the 

 tissue. Eight punctures were counted on a plant not over 2 inches high, and in this 

 field were found an average of from 5 to as many as 16 beetles on and about each plant. 

 In this 15-acre field fully 25 per cent of the cotton stalks had been killed by the attacks 

 of this beetle, and in some small areas as much as half had been killed. * * * 

 They occurred also on neighboring farms, but in no other case in such injurious num- 

 bers. In all cases the owners of infested fields reported that the first appearance of 

 these insects in the cotton was in those portions of the fields that had been in cowpeas 

 the year previous. About three weeks later — May 27 — the injury became less, owing 

 to the more rapid growth of the plants, and perhaps also to the greater dissemination 

 of the beetles. 



HABITS AND LIFE-HISTORY RECORDS. 



The life habits of this species and the length of the life stages were 

 worked out by Doctor Chittenden in 1903 and published by him in 

 1904 in Bulletin 44 of this Bureau. Because of the fact that his 

 records were obtained under unnatural and unfavorable conditions 

 they must be revised somewhat in the light of more recent work. 



THE EGG. 



In preparing the nidus for her egg the female sits quietly on the 

 pod of the cowpea and with her mandibles excavates a cavity through 

 the pod into the pea beneath. The opening is about as large as the 

 diameter of the proboscis of the beetle and about as deep as it is 

 long. After it has reached the proper depth the beetle begins to 

 revolve slowly around the opening, feeding at the same time and 

 evidently preparing a cavity at the bottom of the excavation for 

 the reception of the egg. The curculio is very deliberate in "all her 

 movements and the preparation of the nidus takes from three-quarters 

 of an hour to an hour and a half. After its completion she with- 

 draws her proboscis, turns, crowds the tip of her abdomen close 

 down into the hole, and oviposits. A brief examination with her 

 proboscis to determine that all is well completes the operation. 



The egg lies usually within the pea itself, more rarely in the paren- 

 chymatous tissue between the peas or between the pod and the pea. 

 It may be sunk so slightly in+o the pea as to part from it when the 

 pod is removed or buried so deeply that it can not be seen from the 

 exterior when the pod is opened. This depends on the thickness of 

 the pod and the size of the individual beetle which placed the egg. 

 The egg is pushed in with the end first but lies usually with its long 

 axis more or less parallel with that of the pea. The punctures are 

 made as a rule about one-third of the way around the pod from the 



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