Insect Identification

Question: Hello,
We moved into a townhome last April and noticed a large number of these insects in the backyard (which is enclosed on all 4 sides).  At that time, the yard (20'x20') was grass and we had a few potted plants.  This year there is no grass, just pavers and planting beds along two sides.  We are seeing the insects again and wonder what they are and if they will cause damage to the garden we're dreaming of.  
Thanks in advance for your assistance.

responder: Answered by the Home and Garden Information Center (HGIC), University of Maryland Extension. For timely gardening information and tips, subscribe to our Maryland Grows blog and quarterly newsletter. Follow us on Facebook, Instagram, and YouTube. Replied March 28, 2023, 4:16 PM EDT
response: These appear to be flies, in particular gnats or midges, and more specifically likely fungus gnats. By and large, they are not considered plant pests when they occur outside; sometimes they are a nuisance or may damage delicate plant roots on indoor plants if they become numerous. As with other fly larvae, their larvae require moist substrates in which to feed, so if the yard has a drainage issue or areas of soil tend to stay damp for other reasons, that may be why you're seeing them. They also could simply be flying-in from nearby natural areas; plenty of insects like these begin to emerge in spring and relatively few are garden pests. If these are near sources of night lighting like the light coming through a window or a porch light or lamp post, that's probably what's attracting them to this spot. Other than potentially turning outdoor night lighting off if they become bothersome, nothing needs to be done. If soil drainage issues exist in the yard, on the other hand, they should be addressed before plants are installed unless the plants chosen are selected for their tolerance of occasionally soggy soil.  In the next few weeks, if you see bright orange gnats that look similar in shape and size to these, they might be Boxwood Leafminer adults. It's a very common insect pest of boxwoods but they won't bother other plants. If you suspect you're seeing any of those flies later in spring, feel free to send us additional photos for confirmation. (Even if you do see some but you are not growing boxwood in the garden, nothing needs to be done.)  Miri

responder: The Question Asker Replied April 05, 2023, 11:19 AM EDT
response: Hi Miri, Thanks so much for your reply. Now that the plants are beginning to emerge, I'm seeing additional bugs (see two attached photos of pansy flowers).   Last Fall I purchased 3 mini blueberry plants and 2 Bo Bo Hydrangea to incorporate into our new 2023 gardens.  All were fine and then suddenly lost their leaves overnight. I'm afraid these bugs may have been the culprit.  I see some of the fungus gnats (that you identified for me) on the petals of the pansies along with tiny green and tiny orange/brown bugs.  We don't have standing water but there is underground drainage conduit running through all of the town home backyards.  Do these additional photos give you any more clues? I appreciate your help so much. Laura

responder: Answered by the Home and Garden Information Center (HGIC), University of Maryland Extension. For timely gardening information and tips, subscribe to our Maryland Grows blog and quarterly newsletter. Follow us on Facebook, Instagram, and YouTube. Replied April 05, 2023, 2:00 PM EDT
response: Hello Laura,  The insects on the pansy flowers are aphids, and while sometimes unsightly they usually don't cause plants much damage or need to be treated. The simplest approach to removing most of them (at least for the short term) is to either squish them by hand or blast them off the plant with a strong jet of water from a hose. Plenty of beneficial insects and even small birds will pluck them off the plants and eat them once they discover them, so aphid outbreaks usually don't last very long. In fact, we think we see at least a couple aphid "mummies" already present, which means some beneficial tiny (stingless) wasps have found these aphids and are reproducing. When aphids occur on flowers in particular, we discourage pesticide use (even an organic type) because of the risk to pollinators visiting the blooms. While comparatively few pollinators make use of pansy blooms, it's still not a risk gardeners need to take given how relatively harmless aphid colonies like these are.  Aphids weren't responsible for the leaf loss on the shrubs, and even if they were present on those plants at the time, no serious damage would have resulted. Usually when new plants fail in the first year or two after planting (not to say these shrubs are definitely dead though) it's due to environmental conditions and not a pest or disease. Were the blueberries and hydrangeas planted after purchase that fall, or were they kept in pots for spring planting? (Our interpretation is the latter since you mention 2023 garden.) If kept in pots, the exposure of the root balls to fluctuating winter temperatures (whereas they're much more insulated when in the ground) could have caused root damage or at least root stress. If the pots dried out too much between waterings, or were kept too wet, that also could be a contributing factor. Plus, depending on how late in the season this happened, a frost overnight can also "burn" foliage left on deciduous plants like these, since they do normally shed all of their leaves for winter. (There are a few evergreen-ish blueberry species, but those commonly grown for harvestable crops are not.)  It would be perfectly normal for both blueberries and Panicle Hydrangea (Hydrangea paniculata, the group to which variety 'Bobo' belongs) to remain leafless and not break dormancy until mid-spring or so. (Weather-depending, in a typical year this might be late April for your area.) We suggest giving the plants until May to show signs of new growth before writing them off as potentially dead or weakened to the point of having a hard time establishing. If you prefer, you can share photos with us to see if we can determine if the stems appear withered/shriveled and possibly dead/desiccated.  For future reference, autumn is an excellent time to plant many shrubs, trees, and perennials, though we understand if you couldn't in this case due to an obstacle like not having the planting bed ready at that time. In those circumstances, you can "heel-in" potted plants to insulated them for the winter and reduce how often they'll need checking for water. Heeling-in plants simply entails sinking them into the ground as if you were planting them but without removing their pots; that way, you can just pull them up in spring when ready to plant them in their final locations.  In terms of monitoring them for watering needs, which is key when establishing new plants, feel the soil a couple inches deep (if still in pots) or about five inches deep (if in the ground) and water well only when the soil is becoming somewhat dry to the touch at that depth. Potted plants dry out much faster than those in the ground, especially on breezy days or when we have warm spells like today's heat.  If the conduit is enclosed enough that roots of nearby plants aren't growing into soggy soil, then it's likely a non-issue. If the drainage channel instead keeps that area of ground wetter, then planting moisture-loving or -tolerant species in that area instead would be best. Blueberries sometimes occur in wet soils in the wild, but the soil acidity (pH) needs to be strong to keep naturally-occurring soil-borne diseases that take advantage of soil wetness at bay. Hydrangea as a group aren't great in soggy conditions but the species perhaps most tolerant of wetness is Bigleaf Hydrangea (Hydrangea macrophylla).  If useful, other flowering shrubs that handle moderately wetter soils well include Summersweet (Clethra alnifolia), Buttonbush (Cephalanthus occidentalis), Virginia Sweetspire (Itea virginica), Elderberry (Sambucus canadensis), Steeplebush (Spiraea tomentosa), Swamp Azalea (Rhododendron viscosum), and Leucothoe (Leucothoe axillaris or Leucothoe fontanesiana), all of which happen to be native or nearly-native.  Fungus gnats sitting on any of the flowers are not causing harm and don't need to be managed. Some actually might be valued pollinators for certain plants (not pansies, but other species with less showy flowers). When fungus gnats are numerous indoors and causing a nuisance or minor houseplant root damage, using an organic pesticide to reduce their numbers might be warranted, but when outdoors, they don't need to be treated.  Miri

responder: The Question Asker Replied April 13, 2023, 1:45 PM EDT
response: Hi Miri, I can't thank you enough for your very thorough and helpful response.  I'm in a bit of a learning curve right now as my new garden will be mostly containers with just a bit of in-ground planting.Just for fun, I've attached a few photos of my old garden in Middletown and the new space I'm in the process of creating.  Medicinal herbs are my joy and I'm anxiously awaiting little seedlings.  I appreciate your help so very much.Happy Gardening!LauraOn Wed, Apr 5, 2023 at 2:00 PM Ask Extension <<personal data hidden>> wrote:

responder: Answered by the Home and Garden Information Center (HGIC), University of Maryland Extension. For timely gardening information and tips, subscribe to our Maryland Grows blog and quarterly newsletter. Follow us on Facebook, Instagram, and YouTube. Replied April 13, 2023, 2:22 PM EDT
response: You're welcome, and beautiful garden!