The insect pests recorded and their pest status is given in Table 16. Among these insect pests the Welo bush-cricket (Decticoides brevipennis Ragge), locally it is known as Degeza , is probably a new species to science. This tettigoniid was virtually unknown until the early 1970's when the first outbreaks occurred in Welo province. By 1974, the outbreak had spread to most of the western Welo and the insect had become a major pest of tef, wheat and sorghum. 

Storage insect Pests

According to McFarlane and Dobi (1972), the attacking and damaging effects of eight storage insect pests on tef and wheat were investigated. The pests used for their study were Sitophilus oryzae, Rhyzoperha dominica, Sitotroga cerealella (Oliv.), Trifolium castaneum (Herbst), Trifolium destructor (Uyttenb.), Oryzaephilus surinamensia (L), Cryptolestes pusillus (Schon.), and Ephestia cautella (Wlk.). The results indicated that under experimental conditions, where insects were reared at 27^oC and 70 percent R.H., all the eight species were able to attack wheat, while Trifolium castaneum (Herbst) was the only insect capable of multiplying itself effectively on undamaged whole tef and predominantly fed on the grain embryo. T. destructor Uytt. Ephestia cautella (Wlk) showed some ability to produce surviving progeny on whole tef but is unlikely to become serious pests. Cryptolestes pusillus (Schonh.) was able to infest tef in the presence of other insect species and also multiplied effectively on milled tef, which suggests that, it is the nature of the intact seed that prevents infestation in the absence of T. castaneum. It should be noted that evens this finding was obtained under experimental conditions, where temperature and relative humidity were controlled to create a favourable environment for the insect. Results of experiments conducted in Ethiopia under natural environmental conditions and traditional storage systems, indicate that tef does not incur any loss as a result of damage by any storage insect pests (Table 17). According to Yemane and Yilma (1989), weight loss studies conducted on grains under traditional storage conditions indicated that emmer wheat showed the lowest weight loss of 0.6 percent, followed by tef 1.9 percent, and thus were the only cereals that were not damaged at all. The weight loss of emmer wheat was attributed to rodents while that of tef was attributed to leakage caused to the stores by rodents and birds. The weight loss of maize was 3.5 percent, of wheat 4.2 percent, and of barley 4.5 percent. The report also stated that the nutrient loss of tef under storage conditions was relatively low (Table 8).

Table 16. Insect pests of tef recorded in Ethiopia.

Rodents

Rodents are the vertebrate pests of many crops both in the field and in storage. However, the extent a percentage of the damages and losses incurred is not well known. Beside their direct feeding damage, they are also responsible for damage to quality in such a way that the older tef seeds will change. In some cases rodent faeces are also observed.

Table 17. Physical grain damage by types of grain and storage