{"id":365,"date":"2026-05-28T14:37:43","date_gmt":"2026-05-28T14:37:43","guid":{"rendered":"https:\/\/blog.uvm.edu\/commhort\/?p=365"},"modified":"2026-05-28T14:37:43","modified_gmt":"2026-05-28T14:37:43","slug":"grasshoppers-in-may-whats-going-on","status":"publish","type":"post","link":"https:\/\/blog.uvm.edu\/commhort\/grasshoppers-in-may-whats-going-on\/","title":{"rendered":"Grasshoppers in May?\u00a0What\u2019s\u00a0going on?\u00a0"},"content":{"rendered":"\n

Usually,\u00a0we\u00a0think of\u00a0grasshoppers\u00a0as\u00a0a\u00a0summer or fall\u00a0vegetable pest. That is why we were surprised to hear from a grower with a plague of them in\u00a0his Vermont high tunnel in\u00a0early May\u00a0(Fig. 1).\u00a0\u00a0This grower\u00a0had never\u00a0noticed grasshoppers in the spring\u00a0before\u00a0but, this year\u00a0the\u00a0succulent new growth of\u00a0his\u00a0high tunnel cucumbers has been reduced to lacy shadows of their former selves (Fig. 2).\u00a0\u00a0Becky Maden has\u00a0observed\u00a0grasshoppers in her high tunnel for the past 3 years, and\u00a0it seems\u00a0they\u00a0appear earlier\u00a0every year\u00a0and\u00a0are\u00a0doing\u00a0more damage. There are at least 83\u00a0different species\u00a0of grasshoppers in Vermont alone, and it is unknown what species\u00a0was responsible for\u00a0the damage these\u00a0growers\u00a0observed. However,\u00a0it is\u00a0likely\u00a0the\u00a0special\u00a0microenvironment within a high tunnel can lead to\u00a0unique pest issues not\u00a0encountered\u00a0in field production. <\/p>\n\n\n\n

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Grasshoppers are in the\u00a0order\u00a0Orthoptera, and include what we commonly call locusts,\u00a0katydids,\u00a0crickets\u00a0and grasshoppers.\u00a0There are over 20,000 known species of orthopterans worldwide.\u00a0They have gradual or incomplete metamorphosis, with the immatures (nymphs) hatching from\u00a0an\u00a0egg\u00a0looking\u00a0similar to\u00a0the adult stage.\u00a0Over multiple\u00a0molts\u00a0they\u00a0gradually grow wing pads\u00a0that form wings when\u00a0they reach adulthood. They\u00a0have chewing mouthparts that can consume\u00a0large amounts\u00a0of foliage in a short amount of time. They continue feeding throughout all life stages except the egg. That\u00a0makes them a persistent pest over an extended period.\u00a0Most grasshopper species overwinter as eggs in the soil and\u00a0emerge\u00a0as nymphs when the temperature rises.\u00a0\u00a0The common signs of grasshopper damage\u00a0are\u00a0leaves\u00a0that are skeletonized\u00a0or with\u00a0ragged or tattered edges and fruit with\u00a0chewing\u00a0pits.<\/p>\n\n\n\n

It is impossible to know the life cycle of the damaging grasshopper, without a species determination. However, some general assumptions can be made. As the grower proposed, it is likely the grasshoppers overwintered as eggs in the high tunnel, in the egg stage. He saw a few grasshoppers last fall, but they didn\u2019t ravage his crops the way they have this spring. An individual female grasshopper can lay an average of 10-400 eggs, and they don\u2019t need a male grasshopper for reproduction. That means even one or two adults in the high tunnel in the fall can lead to hundreds of young ones in the spring. <\/p>\n\n\n\n

Becky Maden noticed grasshoppers early in her high tunnels too. They decimated some of the more tender young plants like basil. In grasshopper-infested houses, it is essentially impossible to grow these particularly sensitive crops. This year she sprayed Pyganic\u00ae, a pyrethrin-based biological insecticide) known to provide a quick knockdown and kill for a broad array of pests, including grasshoppers.  She advised applying it at a time of day when they are less active to make sure the spray contacts the pest to maximize on control. Targeting the early nymphal stage is best as they are more likely to be more sensitive to the treatment, and their exoskeleton is softer and more likely to be penetrated by the spray.  Spraying along the edges of the tunnel is important as they may hide in these crevices when not feeding on plants. More than one application may be necessary because the overwintering eggs hatch over for several weeks. When the population isn\u2019t too high, Becky also hand picks them off, dropping them in a container of soapy water and rubbing alcohol. If the population is reduced early, the plants can outgrow the damage. They don\u2019t seem to cause so much damage on tomatoes. Once the cucumbers begin to gain some height, the problem seems to subside. Grasshoppers in her experience don\u2019t climb high into the plant canopies. They also seem to stay off the benches.   <\/p>\n\n\n\n

What other options are there for this pariah?<\/strong> <\/h2>\n\n\n\n

Cultural control.<\/strong> Because the eggs overwinter in the soil, tilling the soil thoroughly in the fall before may destroy the eggs. Weeds around the high tunnel in the summer and fall also may serve as a food source for grasshoppers, so removing them could reduce the adult population that would lay eggs before winter. Theoretically particularly sensitive plants could be protected by careful screening, but grasshoppers are known to chew through cloth screening and once under the screen, they benefit from the protection and their damage may go unnoticed.   <\/p>\n\n\n\n

Insecticides.<\/strong> Several types of insecticides are labeled for use against grasshoppers, though their efficacy can\u2019t be confirmed. Here are a few of them:  <\/p>\n\n\n\n